P0446 Code in 2026: Spiders, Dust, Ice and the Vent Valve You May Not Need

P0446 is one of the few check engine codes where the part named in the quote is often not the part that failed.

Every gasoline car has a sealed fuel vapor system. Vapor from the tank is stored in a charcoal canister and drawn into the engine to be burned. The canister also needs to breathe: when the tank fills, air has to leave, and when fuel is used or purged, air has to come in. That breathing happens through a vent valve and a fresh-air line, usually near the fuel filler or the rear wheel. P0446 — "Evaporative Emission System Vent Control Circuit," which GM and Isuzu call "EVAP Vent System Performance" — means the engine computer commanded that vent and the system did not respond the way it expected.

That is a description of a symptom in the vent path, not a verdict on a valve. We downloaded and read 39 manufacturer documents on the vent side in full — recalls, bulletins, warranty extensions and engineering requests — and the causes they document are, in order of how often they appear: dust and dirt, spiders, water and ice, a valve or its connector, and software. The valve itself is on the list, but it is not at the top.

The federal complaint file does not help much with the code itself. Of 780,071 complaints received by NHTSA from 2015 to September 2026, only 13 name P0446. So we searched for the vent side by its parts — vent valve, vent solenoid, canister vent, vent line — and found 418 complaints. A random 50, read in full, showed what that kind of search is worth: 33 were about the fuel vapor system or fuel-tank venting, 17 matched the words but were about air-conditioning vents, differential vents or other systems, and none of the 50 named P0446. Owners describe the pump clicking off, fuel spitting back and an engine that stalls after a fill-up. The code number depends on the brand; Honda owners report P2422, Nissan owners P0448, Volkswagen owners P2421.

By the end you will know which of five routes your P0446 is on, what each costs in 2026, which recall, extension or bulletin applies, and the cheap cause that gets skipped when a vent valve is quoted first.

Claims marked 🟢 rest on a recall, extension, bulletin or investigation listed in the Sources section; the 39 documents in our published list were downloaded and read in full. Claims marked ⚪ are shop-price estimates carried from our repair guides. Owner-reported figures are what people told NHTSA, published with ODI numbers. The complaint set is a searched set: counts are pattern flags, and every complaint quoted or counted by hand was read in full.

I built PulsCar after a $380 "full diagnostic" in Phuket in 2025 led to roughly $6,000 over six months across several shops (the story is on the About page). This code is a small bill that is easy to make larger, so every claim below that rests on a document names it.

What the vent side does, and why it has its own code

Think of the EVAP system as a closed bottle with two doors. The purge valve is the door to the engine: when it opens, the engine's intake vacuum pulls stored vapor out of the canister and burns it. The vent valve — GM calls it the canister vent solenoid, Nissan the vent control valve, Honda the canister vent shut valve, Kia and Hyundai the canister close valve — is the door to the outside air. It is open almost all the time, so the tank can breathe while you drive and while you fill up. It closes only when the computer wants to seal the system and test it for leaks.

That test is where P0446 comes from. The computer closes the vent, lets the purge valve pull a little vacuum, and watches the fuel tank pressure sensor. If the pressure does not change the way it should when the vent is commanded closed or open, it cannot tell whether the system is sealed, and it flags the vent side. Three different faults produce the same result:

• The vent path is blocked. The valve opens, but no air can get through a nest, a plug of dust or a column of ice. Pressure behaves as if the vent were stuck closed.
• The valve does not move. A seized or corroded valve, or one with no power.
• The measurement is wrong. A tank pressure sensor that reads nonsense, or software that runs the test at the wrong moment.

The documents contain all three. 🟢 GM's PIT6510, from April 2026, is a clean example of the third: on 2023-2026 Colorado and Canyon pickups, "water/snow dripping between the vehicle cab and bed" reaches the fuel tank pressure sensor, freezes over its air reference port, and sets P0446 "at start up." The instruction is to dry it — and, in GM's words, "Do not replace any parts for this issue."

Why this code is not only about emissions. A vent that cannot breathe does two things a driver can notice: at the pump, the displaced air has nowhere to go and the nozzle clicks off; on the road, the purge valve keeps pulling vacuum on a tank that cannot draw in air. 🟢 Mazda's recall 11V-134 describes exactly that on the 2009-2010 Mazda6: "the fuel tank pressure may become excessively negative," and repeated purging "may eventually result in a crack, potentially leading to fuel leakage and an increased risk of fire." That is the reason to treat a hard-to-fill tank as more urgent than the light.

First: is this really P0446? The vent codes side by side

The same failure is reported under different numbers, and the documents use several of them in a single bulletin. Read every stored code before deciding what you have.

The consequence for your wallet: a Honda with P2422 and a Chevrolet with P0446 may need the same thing — a clean fresh-air path. A vent-family code says where to look, not what to buy.

If you also have P0455, P0456 or P0442, read this guide first when the leak codes arrived together with P0446 or with a hard-to-fill tank; read those guides first when they came alone.

The same failed vent, different codes: the maker atlas

Most manufacturers that documented a vent-side problem in the file wrote about the fresh-air path before the valve.

GM, P0446 and its neighbors. Three families of cause: dust (🟢 15-06-04-002 for 2011-2015 Silverado and Sierra, PIC6306 for the 2017-2018 LaCrosse, 23-NA-073 for 2019-2025 pickups), spiders (🟢 PIC6250 and 17-NA-383 for the Sonic, Encore and Trax) and water and ice (🟢 17-NA-233 for the 2016-2019 Cruze 1.4L, PIT6510 for the Colorado and Canyon).

Honda, P2422. 🟢 15-010 (2013-2016 Accord) and 20-056 (2016-2022 Pilot, 2019-2022 Passport): "Dirt may be clogging the EVAP canister vent tube." Honda's tech line article 🟢 ATS 160701 adds that on Accords driven on dry dirt roads the code can come back, and tells dealers to "keep redoing" the bulletin.

Nissan, P0448. 🟢 Five active bulletins for the Frontier, Titan, Sentra and NV replace the filler pipe, drain hose or filter, and two name water in the canister or filter. The Nissan file below explains what they say about the valve.

Kia, P0449 and P2422. 🟢 PS162 (Sorento) and PS532 (Sportage): spider webs in the vent lines. 🟢 FUE038 (Soul, Rio, Forte): water in the canister close valve and "early shut-off during fuel refill."

Subaru, P1449. 🟢 11-123-12 for the 2011-on Forester: ice and snow in the hoses or drain separator "during heavy snow conditions when combined with extended periods of highway driving."

Isuzu, P0446. 🟢 SB19-J-002 for 2012-2019 N-Series 6.0L gasoline trucks in farming, sweeping or off-road use: a new vent valve, covered and relocated.

Volkswagen, P2421. 🟢 Bulletin 01-23-12 for the 2020-2021 Jetta 1.4T: "DO NOT diagnose or replace components" for P242100, "EVAP System Vent Valve Stuck Open," before a software update.

Volvo, P044671. 🟢 Technical Journal TJ 37073 for certain 2025 models: "Do not replace any parts. This is not a hardware-related fault."

Ram, dust without P0446. 🟢 25-001-21: gasoline Ram 1500s in dusty duty set P0441 and fill slowly; a dual filter kit, "Information Only" — FCA's December 2024 parts note calls it customer-paid.

The pattern. Volkswagen and Volvo point at software first. The Isuzu and GM truck bulletins, Nissan's O-ring bulletin and Hyundai's T1L campaign replace a vent valve as the main repair — on the trucks, with a filter or a new location. Everyone else starts with the air path.

The 10-minute P0446 check

1. Read every code, and write down P0449, P0455, P0442, P0456, P0451 or a brand code like P2422 or P0448 if it is there. Note whether the code is current or history.
2. Think about the last two weeks. Dirt or gravel roads, a car wash with the underbody spray, a freeze after a thaw, a car that sat outdoors for months.
3. Remember the last fill-up. Did the nozzle click off early, did fuel spit back, did it take much longer than usual? Did that happen at more than one station?
4. Open the fuel cap and listen. A strong rush of air in or out, repeatedly, suggests the tank cannot breathe.
5. Look at the tank area if you can safely see under the rear. A fuel smell or a wet, stained tank top is a same-day visit, not a code to clear.
6. Find the vent valve and its fresh-air line in a parts diagram. Many sit behind the rear wheel liner or on top of the tank; that changes the labor bill more than the part.
7. Run the VIN at nhtsa.gov/recalls, and on a Nissan or Infiniti ask about NEVAP by name; on a Mazda6 or Kizashi, about the spider recalls.
8. Do not clear the code before a shop sees it if you have a hard-to-fill tank. The freeze frame and the history are evidence.

Eight P0446 situations, and which is yours

"A 2019-2025 Silverado or Sierra, farm roads, P0446 with P0455 or P0449." GM's dust bulletin. Route 1, and the dust section.

"A 2023-2026 Colorado or Canyon, P0446 on a cold morning." Ice at the tank pressure sensor. Route 5.

"A 2016-2019 Cruze 1.4L, P0446 after rain or snow." Water in the canister filter pipe. Route 1.

"A Sonic, Encore or Trax, P0446 or P0455, in spring or summer." Spiders in the canister's fresh-air port. Route 1.

"A Mazda6 2.5L or Suzuki Kizashi, hard to fill." A tank-crack recall. Route 2, today.

"A Nissan with P0448, or any Nissan that will not take fuel." The Nissan file, and NEVAP. Routes 2 and 4.

"The pump clicks off every few seconds, but no code." The vent path or the fill-limit valve in the tank. Route 4, and the section on the refuel stall.

"A new vent valve, and the code is back." Route 1, then Route 4, and the section on why.

The P0446 price ladder, from the bottom up

The cheapest rung that fixes a P0446 is usually a cleaned or protected air path; the most expensive is often reached by replacing parts in the wrong order.

What does it cost to fix P0446 in 2026, and where is the money usually lost? Our cost guides carry a vent valve at $150 to $350 installed, a charcoal canister at $200 to $650, a smoke test at $50 to $150 and work inside the fuel tank at $400 to $1,500. In PulsCar's hand reading of the federal complaints, owners who paid for a vent valve alone name $199 to $600 across six bills and quotes, and owners whose repair included the canister or a blockage name $617 to $1,600 across seven. Where the vent valve is part of the fuel tank, owners were quoted about $1,800 to $2,100 for a new tank. The money is lost when a valve is replaced before anyone inspects the fresh-air line: GM, Honda, Kia, Nissan, Isuzu and Subaru document dust, spiders, water or ice there first, and a new valve does not clear a plugged line.

The five P0446 routes, cheapest first

Route 1 · The air path: dust, spiders, water and ice — $0 to $650

The vent's fresh-air inlet is an open pipe near the ground or the filler neck. Whatever can get into a pipe — dust, mud, water, insects — eventually does, and the documents describe every one of them.

What the documents show. Spiders: 🟢 GM's PIC6250 for the 2012-2017 Sonic and 2013-2017 Encore and Trax gives the cause in one line, "Restriction in fresh air inlet port caused by spiders," and 17-NA-383 tells the technician to "remove the evaporator canister vent cap and Inspect the evaporator canister for spider nesting in the fresh air inlet port." 🟢 Kia's PS532 for the 2017-on Sportage adds a practical warning: webs "will need to be removed with a pipe cleaner. Trying to clear the hose with compressed air has proven to be ineffective and should not be done." Its older PS162 for the Sorento says the same about compressed air, "often ineffective." Dust: 🟢 15-06-04-002 explains the mechanism on the 2011-2015 Silverado and Sierra — the vent "draws fresh air into the EVAP system through a vent attached at the top of the conduit that is secured to the fuel filler pipe," and dirt entering it "may result in restricted air flow." 🟢 PIC6306 for the 2017-2018 LaCrosse: "dust intrusion into the EVAP canister through the air inlet pipe." Water and ice: 🟢 17-NA-233 on the 2016-2019 Cruze 1.4L — "water trapped in the evaporative emission canister filter pipe" — is fixed by a newly designed, relocated filter pipe, a 0.6-hour job under the base emission warranty. GM's earlier engineering request for the same car, 🟢 PIE0455, asked technicians to "Drain any water or remove any ice" from the fresh-air line and to check whether the wheelhouse liner clips were present. 🟢 Subaru's 11-123-12 blames "ice and snow" on the Forester, and 🟢 Honda's 15-010 and 20-056 blame dirt in the vent tube.

What the owners report. A 2012 Impreza owner paid $617.28 after the dealer found "SPIDER WEBS IS EVAP DRAIN & VALVE ASSY" — and was told the repair was not covered by an extended warranty "because it was caused by a spider and not a part defect." A 2020 Sportage owner heard the same argument after yellow sac spiders were found in the lines: "an 'environmental' condition and not mechanical defect." Kia's own PS532 describes that car's spider problem. A 2016 Civic owner's second dust-clogged canister was priced at $700 plus $100 for diagnosis after the first was covered; American Honda agreed to pay "ONE MORE TIME ONLY OUT OF WARRANTY." A 2014 Sierra owner's system was "COMPLETELY COATED WITH FINE DUST," about $800, with GM paying about half; the owner later moved the vent intake out of the dusty wheel well and now blows out the filter every year. And a 2006 Tribute owner's shop found the vent hose at the filler neck "PLUGGED WITH SPIDER WEBS" on a car that "WOULD ONLY ACCEPT 10 DOLLARS OF GAS AT A TIME."

The cheap cause that gets skipped. The fresh-air inlet itself. On many cars it is a small filter or a capped port behind the fuel door or the rear wheel liner, and on GM's Sonic, Encore and Trax it is the vent cap on the canister. A look at it costs a few minutes of labor. Replacing a valve before anyone has looked costs the valve.

Fix it yourself — the honest split. Finding the fresh-air inlet in a parts diagram, removing its cover and looking for webs, mud or a wet filter is a driveway job on many cars. Clearing a web from a hose with a pipe cleaner, as Kia describes, is too. What is not: lowering a tank, pulling a canister buried above the rear axle, or deciding whether dust has reached the charcoal inside.

At the shop — say this: "Before you replace the vent valve or the canister, can you inspect the fresh-air line, filter and inlet for dust, spiders, water or ice, and show me what you find? Is there a bulletin for my VIN about the vent filter?"

Route 2 · Your VIN is on a recall, extension or campaign — $0

No recall names P0446. Several cover the thing that sets it.

What the documents show. 🟢 Mazda6 2.5L. Recall 11V-134 (Mazda 6211B) covered 52,000 2009-2010 cars built from 8 April 2008 to 8 February 2010: clean the vent line, fit a spring to keep spiders out, reprogram the engine computer, and replace the tank and evaporative chamber if the tank was damaged or the vent line restricted. Recall 14V-114 (7214C) followed for about 42,000 2010-2012 cars built from 14 September 2009 to 2 May 2011, because, in Mazda's defect report, "a kind of spider could possibly intrude even with the expanding spring," and nine cracked-tank cases had occurred on cars with only the spring. 🟢 Suzuki Kizashi 2010-2013. Recall 14V-464 (19,249 cars) replaced the vent line with one that has a filter; recall 18V-769 (21,063) came back for the filter — more in the spider section. 🟢 Nissan and Infiniti 2004-2016, plus some 2003 and 2017. The NEVAP program extends the emission warranty on the vapor vent tube between the fuel tank and the canister to "15 years or 150,000 miles, whichever occurs first, if the tube is found to be completely blocked." 🟢 2017 Santa Fe Sport. Hyundai campaign T1L (bulletin 16-01-068) replaced the fuel tank vent valve on cars that "may experience the fuel nozzle prematurely clicking off during refueling." 🟢 Kia's SC135 (about 258,470 2009-2015 Optima, Rondo and Sedona) inspected canisters in 28 salt-belt states and extended canister coverage elsewhere to 10 years or 120,000 miles, for leak codes; for nearly all, the ten years have run out.

Warranty coverage that is not a program. Some bulletins in this file were written to be paid under ordinary coverage: 🟢 GM's 15-06-04-002 under "Bumper-to-Bumper coverage," 🟢 17-NA-233 and PIT6510 under emission coverage, 🟢 Honda's 15-010 and 20-056 with "The normal warranty applies." Under federal law the vent valve and canister are ordinary emission parts: 🟢 42 U.S.C. 7541(i) gives them 2 years or 24,000 miles, and reserves 8 years or 80,000 miles for the catalytic converter, the engine computer and the diagnostic device.

What the owners report. A 2018 Frontier owner was quoted $1,600 with the dealer's own paperwork citing "P0448 SERVICE BULLETIN NTB15-079," then found NEVAP online; Nissan said the enhancement "WAS VIN SPECIFIC AND DID NOT APPLY." Nissan's FAQ lists model years 2004 to 2016, so a 2018 is outside it. A 2013 Maxima owner received the NEVAP letter, brought the car in, and paid $116.05 because the tube was not completely blocked; the dealer quoted $1,200 for a tank. A 2008 Torrent owner learned at the dealer of a special warranty on a cracked fuel pump part, while the vent solenoid found stuck open beside it cost $302.

The cheap cause that gets skipped. The letter. Nissan told owners to put the NEVAP sticker on the front of the warranty booklet, and an owner who bought the car used has usually never seen either. A VIN lookup by the dealer shows it; a lookup at NHTSA does not, because it is a warranty program, not a safety recall.

At the shop — say this: "Can you check my VIN for recalls, emissions recalls, warranty extensions and campaigns, not only safety recalls? And is this repair covered under my remaining bumper-to-bumper or emissions warranty?"

Route 3 · The vent valve, its connector and its fuse — $0 to $600

The valve does fail — but less often than it is replaced, and a vent valve without power looks exactly like a dead one.

What the documents show. 🟢 Isuzu's SB19-J-002 replaces the vent valve on N-Series trucks when "normal diagnostics" show it has failed, then covers and relocates it. 🟢 GM's 15-06-04-002 replaces the Silverado's original valve with "the new revised design assembly," sealed and fed from a remote pre-filter — but opens with a note: "DO NOT replace the EVAP canister assembly for this concern unless it fails the leak test or it has ingested excessive amounts of dirt, dust or water." 🟢 GM's engineering request PIE0528 for 2019 Enclave, XT5, Equinox, Traverse, Acadia and Terrain looked for a leak "at the O-ring interface between the canister body and the CVS" and asked technicians to "document the voltage at the CVS harness when activated." 🟢 Nissan's NTB17-082E for 2008 and newer Nissans (except LEAF and the Titan XD diesel) says the vent control valve's O-ring "is no longer available as a service part," so a leaking seal means a whole valve. 🟢 Volkswagen's 01-23-12 for the 2020-2021 Jetta 1.4T tells technicians not to replace anything for P242100 before a software update. And 🟢 Honda's 15-010 replaces the Accord's canister but has the technician "transfer the original canister vent shut valve and the vent pressure sensor to the new canister." The valve Honda keeps is the valve many quotes replace.

What the owners report. A 2015 Malibu owner's valve was "A $36 PART THAT COST ME A TOTAL OF $600" because the shop had to drop the gas tank to reach it. A 2015 Impala owner paid $198.77 for a vent valve solenoid. A 2010 Sierra owner paid $501.17 for a vent valve stuck open, told it was "A KNOWN PROBLEM BUT NOT COVERED." A 2020 Jetta owner was quoted over $250 for the part and about $200 in labor. A 2020 Silverado owner's dealer replaced the vent valve's harness connector for P0499, and the light was back within 48 hours. And a 2020 Ridgeline owner's vent valve was replaced "Second through forth time," each time with the warning back "within 2 weeks."

The cheap cause that gets skipped. The connector and the power feed. A corroded connector or an open circuit sets the same family of codes as a seized valve, and GM asked for the voltage at the harness before accepting a canister back. A scan tool that can command the valve open and shut — while someone listens for the click — separates the two in minutes.

Fix it yourself — the honest split. If the valve is reachable and your scan tool can command it, listening for the click and checking the connector for green crust is a driveway job. Replacing a valve above the tank is not: it involves lowering a tank with fuel in it, which is the job that turned the Malibu owner's $36 part into a $600 bill.

At the shop — say this: "Can you command the vent valve with a scan tool and check the voltage and ground at its connector before replacing it? If you do replace it, can you also show me the fresh-air line it breathes through?"

Route 4 · Canister, filler pipe, drain hose and the tank — $200 to $3,900

When the air path keeps plugging, or water has already reached the charcoal, the fix moves from the valve to what surrounds it.

What the documents show. 🟢 Nissan's NTB15-079G for the 2005-2019 Frontier replaces the canister, removes the canister filter and replaces "the fuel filler pipe, canister drain hose, and fuel filler cap (on some model years)" for P0448 — a 0.9-hour claim. 🟢 NTB15-075b does the same on the 2006-2015 Titan and says outright that "The vent control valve and pressure sensor will be reused later in the procedure." 🟢 NTB14-044b for the 2013-2018 Sentra replaces the canister hose and discards the box-drain, then has the technician "Inspect the EVAP canister filter and EVAP canister and replace if water is present" — and, if water is found inside the canister, replace the pressure sensor and vent control valve with it. 🟢 Honda's 20-056 fits a "canister drain kit, which includes a canister filter box" on the Pilot and Passport, and allows 0.3 hours to replace the filter box alone when it plugs again. 🟢 Kia's FUE038 replaces the Soul's, Rio's and Forte's "Air Drain Case" when water is found in the canister close valve.

When the vent is part of the tank. Many modern tanks carry their own vent and rollover valves inside or on top of the tank. 🟢 Hyundai's campaign T1L replaced one through the fuel pump opening with a special tool. Where no such procedure exists, the quote is a tank. A 2018 Ram 1500 owner at 43,325 miles was quoted $2,104.64: "Because the vent valve is integrated into the tank, they stated it cannot be serviced separately." A 2012 Patriot owner was quoted "MORE THAN $1800 BEFORE THE TAX" for a rollover vent valve that "DOES NOT OPEN TO RELEASE AIR." A 2017 Golf owner paid $3,896.69 for a tank and canister; fuel "sprayed out" when the dealer removed the canister.

What the owners report about repeat work. A 2013 NV owner, after three trips for a warranty tank part, was quoted $620 for a vent valve and canister with filter. The same 2018 Frontier owner, whose pump "WILL SHUT OFF AND GAS WILL SPIT OUT OF THE FILLER TUBE" was quoted $1,600 for the filler tube, canister, valve and pressure sensor. A 2020 Camry owner paid $1,000 for a canister and vent valve, and wrote "Problem not fixed."

The cheap cause that gets skipped. The drain hose and filter box. On the Nissan and Honda documents above, the new part that stops the problem from returning is a hose, a filter or a drain box that costs a fraction of the canister it protects. A canister replaced without it is a canister that will take in the same water or dust.

At the shop — say this: "Was water or dirt found inside the canister or the filter? If you replace the canister, does the bulletin for my car also replace the drain hose, filter box or filler pipe — and can I keep the original vent valve if it tests good?"

Route 5 · Sensors, software and weather — $0 to $200

P0446 depends on a pressure reading, and a pressure reading can be wrong without anything in the vent being broken.

What the documents show. 🟢 GM's PIT6510, April 2026, for 2023-2026 Colorado and Canyon: "This issue may occur more frequently in changes in between seasons or environments where there is melting and refreezing occurs." Water between the cab and bed freezes on the fuel tank pressure sensor's reference port; the repair is to bring the truck above 32°F, dry the area and reassemble — 1.6 hours under emission coverage — and "Do not replace any parts for this issue." 🟢 Volvo's TJ 37073 for certain 2025 mild hybrids (S60, XC60 and XC90 in NHTSA's index): "Do not replace any parts. This is not a hardware-related fault." The instruction is to erase the code and idle five minutes; if it returns, fault tracing continues, and a software fix is in development. 🟢 Volkswagen's 01-23-12 puts the software update before any diagnosis of P242100 on the 2020-2021 Jetta. And 🟢 Kia's FUE038 is a reminder that the tank pressure sensor code P0451 can be water, not a sensor.

The other half of software: what it cannot see. 🟢 The August 2018 revision of Nissan's NEVAP bulletin begins with an admission: "the OBD II software on certain 2003-2017 vehicles may not accurately pinpoint a complete blockage in the evaporative emission vapor vent tube." It adds that "OBD lamp illumination is not a symptom of the subject condition" — the symptom is a tank that is "consistently extremely hard to refuel" at every station. On those cars the most serious vent blockage may never set P0446 or P0448 at all.

The cheap cause that gets skipped. The weather. A code that appears on the first cold start after a thaw and never on a warm afternoon is pointing at water or ice, and parking the car indoors overnight is a free experiment.

Fix it yourself — what to write down. The date, the outside temperature, whether it rained, snowed or froze the night before, and whether the code was current or history. That page is worth more to the technician than a new valve.

At the shop — say this: "Is there a software update or a bulletin for this code on my VIN? It only sets on freezing mornings — can you check the tank pressure sensor and the fresh-air line for water or ice before replacing anything?"

The spider file: two recalls, a filter that clogged, and a warranty word

A vent line is a small, dark, dry tube with a steady trickle of fuel vapor, and several carmakers found spiders living in theirs.

🟢 Mazda went first, and had to go twice. In February 2010 it added a spring to the canister vent line of the Mazda6 in production to keep spiders out. In March 2011 it recalled the earlier cars without the spring (11V-134). In May 2011 it changed the engine computer software in production to limit how much vacuum the purge system could pull on the tank. Then, in Mazda's own chronology filed with 14V-114, a crack was reported in November 2011 on a car that had the spring; a second in September 2013; and by December 2013, "9 cases," all on cars with "only the spring," none on cars with the new software. Mazda's conclusion: the spring helped, but "a kind of spider could possibly intrude," and the software "is effective to avoid the possibility of the tank cracking, even under such a severe condition as the canister vent line is clogged by a spider web." The second recall reprogrammed the computer.

🟢 Suzuki's version is shorter and says more about the warning light. Its Part 573 report for 14V-464 records that in March 2011 it received "a report from the United States market of a situation involving malfunction indicator lamp (MIL) illumination resulting from a crack in the upper rear side of the fuel tank," found a spider web in the vent line in June 2011, and decided to "monitor field data because the cause of the problem was an external factor and problems could be easily identified by MIL illumination." After seven reports, in July 2014, it recalled all 2010-2012 and certain 2013 Kizashis. The remedy was a vent line with a filter on the end. 🟢 Then 18V-769: Suzuki found that cars "equipped with the canister vent hose spider filter (or the original unfiltered vent hose) and operated on non-paved roads or under dusty conditions can accumulate dust in the vent hose filter," with the same result — "excessive negative pressure in the fuel tank, causing deformation and possible cracking." The second remedy replaced the fuel tank and fuel cap.

Read those two recalls together and the lesson for any car is plain: a vent that cannot breathe can hurt the tank, the warning light is the early signal, and a filter that keeps one thing out can collect another.

🟢 GM and Kia documented the same thing without a recall. GM's PIC6250 and 17-NA-383 replace the canister on Sonic, Encore and Trax for spider nesting at the fresh-air port; Kia's PS162 and PS532 clear webs from Sorento and Sportage vent lines with a pipe cleaner.

Where owners get stuck is the word "environmental." The Impreza and Sportage owners above were both refused because a spider, not a part, was to blame; the Sportage owner was told in so many words it was "environmental." On a car whose manufacturer has published a bulletin about spiders in that line, the refusal is worth challenging in writing with the bulletin number attached; on others, the answer depends on the warranty's wording.

The dust file: GM's pickups, and a filter you now pay for

Dust is the most documented single cause of vent codes in this file, and GM's pickups show how the answer changed over ten years.

🟢 2011-2015 Silverado and Sierra: a redesigned valve, under warranty. Bulletin 15-06-04-002 replaced the original vent valve with a sealed one "vented through a remote pre-filter mounted atop the fuel filler housing," with "improved filtering capacity" — 1.1 hours, "under the Bumper-to-Bumper coverage."

🟢 2019-2025 Silverado and Sierra: an added filter, customer-paid. Bulletin 23-NA-073, first issued in June 2023 and revised four times through March 2025, says owners "who operate their vehicles in extremely dusty environments" can plug the canister and vent solenoid, and that the condition "may be caused the by the normal use of these vehicles operating in severe dusty environments." The fix is an in-line filter between the canister and the air inlet. And the bulletin says it twice, in two ways: "This repair is a customer pay alteration," and "This repair is not a warranty repair." The filter "is meant to be maintenance item that should be checked periodically." It covers 2019-2025 1500s and 2020-2025 heavy-duty trucks, and excludes cab-and-chassis models.

🟢 Everyone else's dust. Isuzu's SB19-J-002 for farm, sweeper and off-road N-Series trucks; Honda's ATS 160701 for Accords on dry dirt roads; Ram's 25-001-21 dual filter kit for severe-duty 1500s, "Information Only"; an FCA parts note from December 2024 telling dealers that "EVAP Fuel Filters are to be checked for restriction / blockage on a regular schedule as indicated in the Owners Manual"; and Suzuki's second Kizashi recall.

If you drive on gravel, budget for the filter as maintenance and ask for the bulletin by number; a shop that does not know it may sell a canister and a valve that plug again.

The Nissan file: why the new valve came back

Nissan's P0448 bulletins are the clearest record in the file of a manufacturer changing its mind about which part to replace.

🟢 NTB15-079 for the Frontier was first published in September 2015 and cancelled in February 2016. It returned in November 2016 with "Steps added to apply EPT foam to seal the fuel filler pipe." In April 2020 the amendment history records: "References to vent control valve and pressure sensor replacement removed." The current version, NTB15-079G from February 2022, replaces the canister, filler pipe, drain hose and — on 2011 and older trucks — the cap. 🟢 The Titan bulletin NTB15-075b made the same change in July 2020, and the 2016-2019 Titan bulletin NTB19-037a lists the vent control valve and pressure sensor under "Remove and reuse." 🟢 NTB16-122A, for the 2015-2017 Frontiers built after the April 2015 cut-off, now reads simply "This bulletin is no longer active."

In other words: for P0448 on these trucks, Nissan's instruction is to keep the vent valve the code names and replace the parts around it. The Sentra bulletin is the exception: when water is found inside the canister, it replaces the canister, pressure sensor and vent control valve together. A 2018 Sentra owner's complaint shows why the whole set matters: the valve alone was replaced in October 2024, and the problem was back three months later.

NEVAP sits beside those bulletins and covers something different: the vapor vent tube between the tank and canister, on 2004-2016 Nissans and Infinitis, when it is completely blocked and the car is extremely hard to fill at every station. It does not cover a P0448 repair as such, and Nissan says the check engine light is not its symptom.

What 418 vent-side complaints show

The search set is built from the vent's parts, so it is a map of where owners notice the vent side, not a count of P0446.

By code. Across the whole complaint file, 13 complaints name P0446 — four Toyotas, three Pontiacs, and one each from Mazda, Chevrolet, Volkswagen, Ford, BMW and Mitsubishi. 14 name P0449, led by Chevrolet and GMC; 7 name P2422, five of them Hondas; 5 name P0448, four of them Nissans; 4 name P0498, 3 P0499 and 3 P2421. A separate number stands out: 173 complaints name P1450, and 168 of them are Fords — Ford's code for too much vacuum in the tank, the purge-valve story of recall 18V-735 covered in our P0456 guide.

The 13 that name P0446, read in full. Three 2007-2008 Pontiac G6 owners describe a fuel smell or a leak on top of the tank; a 2009 Silverado 2500 owner, a cracked tank port. Toyota owners describe recurring evaporative codes on a 2002 Camry and a 2003 Corolla, and another 2003 Corolla owner a canister fault; a 2001 Corolla owner's P0446 appears only in a forum link. A 2021 BMW X3 owner reports hard starting after refueling, and a 2021 Atlas owner stalling, then a purge valve and canister. Three report P0446 among other faults or without a diagnosis.

By pattern. Across all 418: 150 mention a vent valve or vent solenoid by name, 69 mention refueling or the pump, 19 name another vent-family code, 15 mention spiders and 9 dust or dirt. Those are word counts.

50 of the 418, read in full

We drew 50 of the 418 at random (Python's random.sample, seed 20260926), read every narrative to its end, and coded each one.

Is the set about the right thing? Only partly. 17 of the 50 matched the words but not the system: air-conditioning and heater vent controls, differential and transfer-case vents, a transmission vent tube, a frozen crankcase vent line, rusted fuel lines in a vent-tube casing and a motorcycle.

What the 33 about the fuel vapor system describe.

The line that matters. None of the 50 names P0446. The codes that appear are P0499, P1449, P2421, P0447 with P0462, and P0441. Owners report what they notice — the pump, the smell, the stall — and the code, when they give one, is their brand's number.

The honest limits. One reader, one pass, no second coder; at 33 relevant reports, a share near one third carries a margin of about 16 points either way. Complaints over-represent bad outcomes. The per-report coding is in the published file.

The refuel stall is not P0446 — but it lives next door

Twelve of the 33 relevant reports describe a stumble or stall right after a fill-up. That story belongs to the other end of the canister, though owners and shops often lump it in with the vent.

When the tank is overfilled, or a valve at the top of the tank that is supposed to stop liquid fuel sticks open, liquid gasoline reaches the charcoal canister. The next time the purge valve opens, the engine gets a slug of fuel instead of vapor. 🟢 Chrysler's 14-001-16 describes it on 2004-2005 Caravan and Town and Country minivans built from September 2003 to March 2004: "The integral multi-functional control valve may stick allowing liquid fuel to enter the evaporative emissions system causing a rich fuel condition when the purge system is initiated." The fix was a new tank and canister, and the owner letter that accompanied 🟢 warranty bulletin D-16-02 (X60) extended the tank's warranty "to 15 years/unlimited miles," with reimbursement. For cars built in 2003 and 2004, those fifteen years have now passed.

How to tell the two apart. A stall within minutes of a fill-up points at liquid fuel in the canister. A light with P0446 and no drivability symptom points at the vent. A tank that is hard to fill at every station can be either, which is why the inspection starts at the fresh-air end.

One more neighbor with a safety recall. 🟢 25V-794 (2021-2024 Kia K5 1.6T, 250,547 vehicles) and 25V-796 (2020-2023 Hyundai Sonata 1.6T, 85,043) describe the opposite pressure problem: a failed purge check valve can let "pressurized air" into the tank, which "may expand and contact the hot exhaust pipe components, which can melt the fuel tank," in Kia's owner letter. Hyundai's bulletin for the Sonata names P0451 (revised to P14EE00), not P0446. If you own one of those cars and the tank area looks swollen or smells of fuel, stop driving it and call the dealer.

What owners say they paid, by lane

Twenty-one figures from owners who reported vent-side repairs to NHTSA, every complaint read in full. They are bills, quotes and estimates as owners reported them, not invoices, and they are published with ODI numbers.

Three figures explain the spread. The $36 valve that cost $600 because the tank had to come down. The $463.08 valve and solenoid on a 2012 Escape, after which the dealer said the tank itself was the problem and estimated another $1,000. And the $617.28 Subaru spider repair — the only vent-blockage figure in the file where the owner reports the problem fixed, and the one a warranty refused.

Why P0446 comes back after a new vent valve

Why does P0446 come back after a new vent valve, and what should be checked before a second one? Most often because the valve was not what failed. In the 39 manufacturer documents PulsCar read, GM, Honda, Kia, Isuzu and Subaru trace vent codes to the fresh-air path first — dust, dirt, spider nests, water and ice — Nissan points at water, and Nissan's Frontier and Titan P0448 bulletins reuse the original vent valve while replacing the canister, filler pipe and drain hose. A new valve in a line that is still plugged fails the same test, and on trucks that keep driving on dirt, GM's own bulletin calls the filter a maintenance item. Before paying for a second valve, ask the shop to command the valve and measure its connector, photograph the fresh-air line and filter, look for water in the canister, and check the VIN for a bulletin or a software update.

The other reasons, from the complaints: a valve fitted to a tank whose built-in vent was the real fault, as the Escape owner found, or a valve that cannot be sold separately, as the Ram owner was told; a car that keeps ingesting dust or water because the drain hose or filter box was not part of the repair; and a weather-driven code that simply returned with the next freeze.

Can you drive with P0446?

Usually, yes. This code rarely changes how the engine runs.

P0446 alone, no fuel smell, normal fill-ups. Drive it, and get it looked at within a few weeks; it will fail an emissions inspection, and a lit check engine light hides any new code that arrives behind it.

P0446 with a hard-to-fill tank, fuel spitting back, or a loud rush of air at the cap. The tank may not be able to breathe. Have it checked within days, and on a 2009-2012 Mazda6 2.5L or a 2010-2013 Kizashi, run the VIN today.

P0446 with a fuel smell, a wet tank top or a swollen tank. Do not park it in a garage, and do not keep driving it. That is a leak, not a code.

A stall after refueling. Not P0446's usual story, but a real hazard in traffic; fill only until the first click, and have the canister and tank valves checked.

Can you drive with a P0446 code, and for how long? Usually yes, for days or a few weeks, because the vent side of the fuel vapor system rarely affects how the engine runs; the car will fail an emissions inspection, and the lit lamp can hide a new code. The exception is a vent that cannot breathe. In the manufacturer documents PulsCar read, Mazda's recalls 11V-134 and 14V-114 and Suzuki's 14V-464 and 18V-769 describe blocked vent lines on the Mazda6 and Kizashi that let tank vacuum build until the fuel tank could crack and leak. If the pump clicks off every few seconds at every station, fuel spits back, you smell fuel, or the tank looks deformed, stop treating it as an emissions code: keep the car out of the garage, fill only to the first click, run the VIN, and have the fresh-air line and tank inspected before any part is ordered.

Should you buy a used car with a P0446 history?

Usually yes. Ask for the repair order: a cleaned line, a filter, a drain hose or a bulletin number is a closed case; three vent valves in two years is an open one. On a 2009-2012 Mazda6 2.5L or a 2010-2013 Kizashi, confirm the recalls are completed. On a 2004-2016 Nissan, fill it yourself before buying — a tank that will not take fuel is the NEVAP symptom. On a pickup used off pavement, ask whether GM's dust filter was fitted. A fuel smell near the tank is a reason to put it on a lift before signing.

Clearing P0446 before an inspection

Clearing the code resets the readiness monitors, and the evaporative monitor is one of the slowest to complete; many cars need several drive cycles and particular fuel levels and temperatures before it runs again. An inspection station will see an incomplete monitor, or the code again if the fault is real. Fix the air path, valve or canister, drive until the monitor reports ready, and keep the repair order. A vent code that appears only in freezing weather may pass a warm-day inspection and return with the first frost.

What a shop actually does with a P0446, checkpoint by checkpoint

1. Reads every code and the freeze frame, noting P0449, P0455, P0442, P0451 or a brand code, and the ambient temperature when it set.
2. Checks the VIN for recalls, emissions recalls, warranty programs such as NEVAP, and bulletins.
3. Commands the vent valve with a scan tool and watches tank pressure respond, then measures voltage and ground at the connector.
4. Inspects the fresh-air line, filter and inlet for dust, spiders, water and ice, and photographs what it finds.
5. Smoke-tests the system for leaks at the canister, valve O-ring and filler neck.
6. Checks the canister and filter for water or dirt before replacing either.
7. Replaces only what failed, plus the filter, drain hose or relocation the bulletin calls for.
8. Clears codes and drives the evaporative monitor to completion, or tells you how many cycles it will need.

Three P0446 traps that cost owners the most

Trap 1: the valve before the line. A vent valve is the part named in the code, so it is the part quoted, and on the documents above the line is the likelier fault. Lesson: ask to see the fresh-air path before paying for the valve.

Trap 2: the "environmental" refusal. Spider and dust repairs are refused as outside influences, even on cars whose makers published bulletins about them. Lesson: bring the bulletin number and ask in writing; on an extended warranty, read the exclusion.

Trap 3: the canister without the drain. A canister replaced without the drain hose, filter box or relocation that stops the water or dust reaching it will plug again. Lesson: ask whether the bulletin for your car includes those parts, and insist they come with it.

Three P0446 quotes, decoded

These are composite scenarios, not individual customers: each combines details that come up repeatedly in owner reports and shop quotes.

Scenario 1: 2021 Silverado 1500, 58,000 miles, farm roads, P0446 and P0455, quote $620 for a canister and vent valve. A second shop pulls the vent hose, finds it packed with fine dust, and fits GM's 23-NA-073 filter with a cleaned line for about $180, customer-paid. The owner adds the filter to the oil-change checklist. Lesson: on a dusty truck, the filter is the repair and the valve is the symptom.

Scenario 2: 2014 Nissan Frontier, 96,000 miles, P0448 and a slow fill, second vent valve quoted at $320. The dealer follows NTB15-079G: new canister, filler pipe and drain hose, the original valve reused, about $700. Lesson: when the manufacturer stopped replacing the valve for this code, a second one is money spent twice.

Scenario 3: 2017 Chevrolet Trax, 44,000 miles, P0446 in June, quote $380 for a vent valve. A technician removes the canister vent cap and finds a spider nest in the fresh-air port. GM's bulletin calls for a canister, about $450 out of coverage, but the owner has seen the cause. Lesson: a photo of the cause is worth asking for, even when the bill is similar.

The P0446 plan: 10 minutes, today, this week

In the next 10 minutes: read every code; note the weather and the last fill-up; open the fuel cap and listen; look under the rear for a fuel smell or a wet tank; and do not clear the code if the tank is hard to fill.

Today: run the VIN at nhtsa.gov/recalls and ask a dealer about warranty programs by name — NEVAP on a 2004-2016 Nissan or Infiniti, the spider recalls on a Mazda6 or Kizashi; find the vent's fresh-air inlet in a parts diagram and, if you can reach it, look inside.

This week: have the valve commanded and the fresh-air line inspected before any part is ordered; ask for the bulletin number that matches your car and for the filter or drain parts it includes; and if a warranty refuses a spider or dust repair on a car with a published bulletin, write to the manufacturer and file your own NHTSA complaint.

If you are not sure whether a sound you hear near the tank or under the hood is related, PulsCar's free sound check screens a 30-second recording of your car. It does not read codes; it is a second opinion on what the car sounds like.

Sources and documents

Primary documents only. Where a claim in this guide is marked 🟢, it rests on one of the items below, and the reference is given so you can pull the document yourself. Claims marked ⚪ are shop-price estimates carried from PulsCar's repair guides — estimates, not measurements from a dataset we own.

1. NHTSA recalls 11V-134 and 14V-114 (Mazda 6211B and 7214C): owner letters and the 14V-114 Part 573 defect report with chronology; Mazda6 2.5L.
2. NHTSA recalls 14V-464 and 18V-769 (Suzuki VG and CY): Part 573 report and 2019 owner letter; Kizashi.
3. NHTSA recalls 25V-794 and 25V-796 (Kia SC356, Hyundai 286): owner letters; Hyundai TSB 25-01-001H (campaign 9B1).
4. GM PIC6250, 17-NA-383, 15-06-04-002, PIE0455, 17-NA-233 (two versions), PIC6306, PIE0528, 23-NA-073 (June 2023 and March 2025 versions), PIT6510. Isuzu SB19-J-002.
5. Honda Service Bulletins 15-010 and 20-056; Tech Line ATS 160701.
6. Nissan NTB15-079G, NTB15-075b, NTB19-037a, NTB14-044b, NTB13-102a, NTB16-122A, NTB17-082E; NEVAP OBD II EVAP Tube Warranty Enhancement, March 2017 and August 2018 (NHTSA 10109198, 10145053).
7. Kia PS162, PS532, FUE038, SC135 and its question-and-answer sheet (WTY009). Hyundai 16-01-068 and campaign T1L notice.
8. Chrysler/FCA 14-001-16 and warranty bulletin D-16-02 (X60) owner letter; Ram 25-001-21; parts note on fuel vapor canister filter 04627332 (December 2024). Subaru 11-123-12. Volkswagen 01-23-12 and VWP-25-06. Volvo TJ 37073.
9. 42 U.S.C. 7541(i)(1) and (i)(2): 2 years or 24,000 miles for emission-related parts; 8 years or 80,000 miles for the catalytic converter, electronic emissions control unit and onboard diagnostic device.
10. PulsCar analysis of NHTSA public data, September 2026: 13 complaints naming P0446, a 418-complaint vent-side search set with a random 50 read in full, 21 owner-reported amounts, and 39 documents. Data and method.

For the neighboring codes and symptoms: P0455 large leak, P0456 very small leak, P0442 small leak, car smells like gas, car stalls while driving, check engine light on and the code index. For the cars: Silverado, Sierra 1500, Accord, Pilot, Altima and Rogue.

Methodology. The vent-side complaint set is a full-text search of NHTSA's complaint file for the vent's parts and related wording, plus every complaint naming P0446; flags are computed by pattern. A random 50, drawn with a fixed seed, was read in full and its coding published; every complaint quoted or counted by hand, and every dollar figure, was read in full. Recall searches cover NHTSA's file from 2010, and manufacturer communications from 2015. Owner figures are not invoices. Nothing here is a failure rate.

Prices verified July to September 2026 in the repair guides they are carried from, and reviewed quarterly. Technical documents verified September 2026: the 39 documents in our published list — among them Mazda's 14V-114 defect report, Suzuki's 14V-464 report and 18V-769 letter, GM 23-NA-073 and PIT6510, Nissan NTB15-079G and the NEVAP enhancement, and Honda 20-056 — were downloaded from static.nhtsa.gov and read in full on 25 September 2026, when the complaint, recall and bulletin files behind our analysis were also queried.

Had a P0446 fixed by a cleaned line, a filter, a bulletin or a warranty program — or refused one? Email [email protected] with the vehicle, mileage and outcome.