P0172 Code in 2026: Fuel in the Oil, Leaking Injectors, and What Honda Covered

P0172 is a code about fuel the engine did not ask for — or thinks it did not ask for.

Every modern gasoline engine meters its fuel, then checks its own work with an oxygen or air-fuel sensor in the exhaust. When the exhaust says the mixture is rich, the computer trims fuel away; when it says lean, it adds fuel. It keeps a short-term correction for the moment and a long-term correction it learns over days. P0172 — "System Too Rich, Bank 1," which GM calls "Fuel Trim System Rich" and Honda and Mazda "fuel system too rich" — means the computer has been taking fuel away from bank 1 and has run out of room to take away more.

That is a statement about a correction, not a verdict on a part. We downloaded 119 manufacturer documents and recall letters that deal with P0172 — service bulletins, warranty extensions, emission recalls, owner letters, dealer messages and engineering notes from Honda, Acura, GM, Ford, Toyota, Lexus, Mazda, Nissan, Infiniti, Jeep, Ram, Isuzu, Mercedes-Benz and Kia — and read 117 of them in full; two exist only as images and are known from NHTSA's summaries. 108 name P0172 in their own text. The causes they document fall into five groups: fuel collecting in the engine oil, software that misjudges the mixture, air or ethanol the computer did not account for, injectors, and fuel pressure.

The federal complaint file is dominated by one car. Of 780,071 complaints received by NHTSA from 2015 to September 2026, 87 name P0172, and 50 of those are Honda CR-Vs. We went through all 87 and sorted them twice, independently, by the same written rules; the two sortings matched on 91% of them (79 of 87). In 45 of the 87, injectors were diagnosed, replaced or recommended. In 41, the owner describes several warning lights or messages coming on at once. And 68 of the 87 arrived from 2023 onward.

By the end you will know which of five routes your P0172 is on, what each costs in 2026, which recall, extension or bulletin applies to your VIN, and the cheap cause that gets skipped when a set of injectors is quoted first.

Claims marked 🟢 rest on a recall, extension, bulletin or letter listed in the Sources section; the documents in our published list were downloaded and gone through in full unless marked otherwise. Claims marked ⚪ are shop-price estimates carried from our repair guides. Owner-reported figures are what people told NHTSA, published with ODI numbers, and every complaint count here comes from all 87 complaints, sorted and published.

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). P0172 is a code where the order of the checks decides whether the bill is an oil change or a set of injectors, so every claim below that rests on a document names it.

What P0172 says: a computer taking fuel away

Fuel trim is the number to know. Short-term fuel trim is the correction right now; long-term fuel trim is what the computer has learned. Positive numbers mean it is adding fuel, negative numbers mean it is removing fuel. P0172 lives at the negative end. 🟢 GM's 22-NA-056, for 2.0-liter turbo engines, gives the numbers a technician should see when the cause is fuel in the oil: "Confirm the long term fuel trim is a large negative number (-18% to -30%)." It then adds a test worth knowing: "If the MAF sensor is unplugged and the long term fuel trim does not move into a normal range of (-10% to +10%), then check crankcase oil level for being overfilled and having an excessive fuel odor."

Extra fuel, or a miscount. A computer can see a rich mixture for two different reasons. Fuel may be arriving that it never commanded — from the oil, a leaking injector, a stuck-open purge valve, a fuel pressure fault — or it may be injecting fuel for a quantity it has counted wrong: software that misjudges a cold start, an air duct that has come off after the airflow sensor so the computer fuels for air that never reaches the cylinders, or an ethanol estimate that is wrong. The documents in this guide contain both kinds, and the fixes are opposite: extra fuel needs its source removed; a miscount needs software, the air path or the fuel estimate fixed, and new fuel parts will not help.

Why fuel ends up in the oil. Direct-injection engines spray fuel straight into the cylinder, and on a cold engine some of it reaches the cylinder walls and slips past the rings into the crankcase. On a long drive it boils back out; on short trips it collects. The crankcase ventilation then feeds those fuel vapors back into the intake, where the computer sees fuel it never injected. 🟢 Mazda's service alert SA-026/18 says it in the maker's own words: "the engine oil may become diluted with fuel and the engine oil level will increase," and "This causes the air fuel ratio to become rich." 🟢 GM's 18-NA-246: "This condition may be caused by driving the vehicle in short intervals, allowing excessive fuel to collect in the crankcase."

Why this code is not only about emissions. A mixture rich enough to set P0172 can foul spark plugs and damage a catalytic converter over time, and when the source is a leaking injector or a fuel line, the same fuel is somewhere it should not be. That is why a fuel smell or a rising oil level outranks the code itself.

First: which fuel-trim code do you have?

The consequence for your wallet: P0172 alone on a car driven on short trips is an oil story first. P0172 with P0300-P0304 on a Honda 1.5-liter is an injector story, and a VIN story. P0172 with P0299 or P0101 on a GM 1.5-liter turbo points first at the charge-air duct — a free recall on 2019 models, a bulletin repair on 2018 and 2020-2022. P0172 with P0175 on a flex-fuel V8 is about what went into the tank. Our P0171 guide and P0174 guide cover the lean side in the same detail.

The maker atlas: who wrote about P0172, and what they blamed

Honda and Acura: software, then injectors. 🟢 The 2018-2019 campaign for 2016-2018 Civic and 2017-2018 CR-V 1.5-liter engines — bulletins 18-114, 18-124, 18-137, 18-147, 19-012, 19-025, 19-026, 19-027, 19-032, 19-033, 19-037, 19-038 and five owner letters — updates software, changes the oil and in some cases replaces or reprograms the A/C control unit. 🟢 23-026 fixes a cold-start miscalculation on 2018-2022 Accord 2.0-liter cars; Acura 23-010 prescribes the same update for RDX and TLX without stating a cause. 🟢 22-002 replaces injectors on 2015-2016 Fits. 🟢 Twenty-six dealer messages from June 2021 to October 2023 asked for specific parts from 1.5-liter Accords, CR-Vs and Civic Sis whose problem dealers had traced to the injectors. 🟢 25-044 gives the repair for leaking injectors on 2023-2024 and early-2025 hybrids.

GM: fuel in the oil, and a loose duct. 🟢 18-NA-246 and 22-NA-056 for the 2.0-liter turbo (LTG); 🟢 PIP5651, PIP5710, PIE0569, service update N192266090, emission recall N192271200 and 22-NA-224 for the charge-air cooler tube on 1.5-liter Equinox, Malibu and Terrain; 🟢 Special Coverage 12313 for a leaking fuel pump seal on 2010-2011 2.4-liter engines; and smaller notes on E85, intake air, aftermarket fuel pumps, camshaft actuators swapped during engine repair on the 2.7-liter (PIP6115) and a 48-car engine-computer fix on the 2018 Malibu (18009).

Ford: ethanol learning, software, injectors — and water. 🟢 SSM 48573 and 49050 (F-150 5.0-liter flex fuel), TSB 21-2443 (software on the same trucks), 18-2310 and 20-2324 (2018 F-150 2.7-liter injectors), and Transit bulletins 17-0014 and 19-2091 (which supersedes 18-2321) about water getting into the engine compartment.

Toyota and Lexus: flex fuel, and a test that sets the code. 🟢 T-SB-0166-19 for 3UR-FBE Tundra and Sequoia; four Tech Tips warn that a scan-tool injection test can itself store P0172.

Mazda, Nissan, Infiniti, Isuzu, Mercedes-Benz, Jeep, Ram. 🟢 Mazda's SA-026/18 (short trips) and 01-019/18 (software on early 2013 CX-5 2.0L cars); Nissan's NTB15-115 (2015 Altima 2.5L); Infiniti's ITB11-054A; Isuzu's SB21-J-001 (injectors were not the cause); Mercedes-Benz's LI07.70-P-078520 (fuel boiling on the M254); Jeep software flashes for the Grand Cherokee 3.0L diesel and the Wrangler JL; and a Ram STAR case that points to a damaged camshaft alignment pin.

The pattern. Where the maker could see extra fuel, it was mostly fuel in the oil or a leaking injector. Where it could not, it was software. And GM and Mercedes-Benz put in writing that hardware should not be replaced until it is proven to be the cause, while Isuzu found that the injectors it got back were not what set the P0172.

The 10-minute P0172 check

1. Pull the dipstick with the engine cold and the car level. Note the level against the last oil change, and smell it. Oil that has risen, or smells of gasoline, is the first answer.
2. Read every code, current and history, and keep the freeze frame. Write down P0175, P0300-P0304, P219A-D, P0299, P0101, P0087 or P0191 if present.
3. Look at the fuel trims if your reader shows live data: large negative long-term numbers (GM's 22-NA-056 cites -18% to -30%) are the rich condition GM describes; read them on a warm engine at idle so readings compare.
4. Think about the driving. Mostly trips under ten minutes in cold weather? Mazda defines an "extremely short trip" as one that ends while the blue cold-coolant light is still on, or within five minutes of it going out.
5. Think about the last fill-ups on a flex-fuel vehicle: small top-ups, a switch between E85 and regular.
6. Smell around the car after a drive, including the engine bay and the fuel door. A raw fuel smell is a same-day visit.
7. Watch the dash. Several warning lights at once with P0172 on a Honda is a documented owner pattern, not a coincidence.
8. Run the VIN at nhtsa.gov/recalls, and ask a dealer for emission recalls, warranty extensions and campaigns by name.

Eight P0172 situations, and which is yours

"The oil level has gone up and smells of fuel." Route 1, today.

"Short trips in winter, a 2.0-liter GM turbo or a Mazda, no other symptom." Route 1.

"A 2018-2022 Accord 2.0L, P0172 on cold mornings only." Route 2 — Honda's 23-026.

"A 2019 Equinox, Malibu or Terrain 1.5L that stalls at idle." Route 3 and the free recall.

"A flex-fuel truck, P0172 with P0175 after a fill-up." Route 3.

"A 2017-2019 CR-V, all warning lights on, P0172 with P0300-P0304." Route 4, and the Honda file.

"A 2018-2021 Stinger, a Kia Sorento or a GM 2.4L that stalls or smells of fuel." Route 5.

"New injectors, and the code is back." Route 1, then the section on why.

The P0172 price ladder, from the bottom up

Read it from the top: the first four lines cost little or nothing and decide whether any of the rest is a candidate. The injector figure comes from our fuel injector cost guide, the pump from our P0087 guide and the oil change from our oil change cost guide, so the numbers match across pages.

What does it cost to fix P0172 in 2026, and when is a set of injectors the wrong purchase? Our repair guides carry an oil and filter change at $35 to $140, a PCV valve at $110 to $220, a purge valve at $150 to $300, a direct-injection injector at $350 to $700 each installed and a high-pressure pump at $500 to $1,500. In PulsCar's review of the 87 federal complaints that name the code, owners who paid or were quoted for injector replacement on a Honda name $1,300 to $2,300, a median of $1,689 across eleven figures. Injectors are the wrong purchase when the oil smells of fuel after short trips, which GM's 2.0-liter bulletins say new injectors will not fix, and when a software update or a free recall applies, as on the 2018-2022 Accord 2.0-liter and the 2019 GM 1.5-liter turbo models.

The five P0172 routes, cheapest first

Route 1 · Fuel in the oil: short trips, cold starts and the crankcase — $0 to $220

This is the route most generic code lists never mention, and the one the documents mention most.

What the documents show. 🟢 GM's 18-NA-246, revised to version 7 in March 2022, covers 2.0-liter turbo engines in the Regal, ATS, CTS, Camaro, Equinox, Malibu, Traverse, Terrain and Envision. Its cause: "This condition may be caused by driving the vehicle in short intervals, allowing excessive fuel to collect in the crankcase." Its instruction on parts is the sentence to show any shop: "Replacing fuel components such as the high pressure fuel pump or fuel injectors will not correct the setting of P0172 under the operating conditions described unless those components can be verified as causing a fuel rich condition." The repair is an oil and filter change, a new primary PCV valve on 2016-2019 models whose engines were built before 7 May 2019, and an engine computer update on 2016-2018 models. Then the warning for the owner: "If the customer continues to frequently operate the vehicle in this manner, they MUST change the engine oil and filter more frequently than the oil life monitor indicates." 🟢 22-NA-056 carries the same story into 2020-2022 and adds the fuel-trim test quoted at the top of this guide, and a note that "P06DE and/or P0521 may or may not be set due to a fuel enriched engine oil condition."

🟢 Mazda's SA-026/18, for Mazda3, Mazda6, CX-3, CX-5, CX-9 and MX-5 models from 2013 to 2019 (the years vary by model), is titled "ENGINE OIL DILUTED WITH FUEL CAUSES P0172:00." It defines an extremely short trip as one where the engine is switched off while the blue low-coolant-temperature light is still on, or within five minutes of it going out, and the explanation it gives dealers to pass to owners recommends that they "immediately check and replace the engine oil and filter when the Check Engine Light turns" on.

🟢 Honda's 2018-2019 campaign for 1.5-liter engines belongs here too. Its extension bulletins give the cause only as "certain driving patterns and environmental factors," but Honda's dealer message announcing the extension on 5 April 2019 is plainer: "This warranty extension addresses concerns related to engine oil dilution due to various control unit software threshold settings and possible camshaft and rocker arm failures." The repair changes the oil — and, in nearly the same words across the campaign, "Drain and refill the engine oil (3.4 quarts). Do not replace the oil filter." The Honda file below has the rest.

What the owners report. In the 87 complaints, 4 describe fuel in the oil or the 2018-2019 Honda campaign without an injector diagnosis. A 2018 CR-V owner writes: "Believe fuel mixing with oil," and later, "Changed oil and problem went away." Another 2018 CR-V owner, at 4,525 miles, had the campaign done and found, less than 700 miles later, "MY OIL ALREADY SMELLS OF GAS." Several of the injector complaints in Route 4 also mention fuel in the oil — a 2017 CR-V owner's dealer quoted injectors and noted "GASOLINE DILUTING THE ENGINE OIL."

The cheap cause that gets skipped. The dipstick, and the calendar. A rising oil level and a gasoline smell are visible for free, and a winter of five-minute trips explains them. A set of injectors does not change either.

Fix it yourself — the honest split. Checking the level against the last change, smelling the oil, changing oil and filter early, and adding a longer drive each week are all owner jobs. So is keeping a note of trip lengths for a fortnight. What is not: deciding whether the fuel is coming from the rings on cold starts or from a leaking injector, which takes a cylinder-by-cylinder test.

At the shop — say this: "Before replacing injectors or a pump, can you check the oil for fuel and the level against my last change, and look at the long-term fuel trim before and after an oil change? Is there a bulletin for my engine about fuel in the crankcase?"

Route 2 · Software, and a computer that miscounts the mixture — $0 to $200

A computer can set P0172 because it counted wrong, and several makers fixed exactly that with software.

What the documents show. 🟢 Honda's 23-026, revised in May 2024, for 2018-2022 Accord 2.0-liter cars: "During engine start in cold conditions, a miscalculation in the PCM causes the air-fuel ratio to exceed DTC rich criteria." And: "This issue is most common in regions with cold weather." The fix is a software update, a throttle reset and idle relearn, and an oil change — and "The normal warranty applies." 🟢 Acura 23-010 gives the same fix to 2019-2023 RDX and 2021-2023 TLX models other than the Type S. 🟢 Mazda's 01-019/18 for early-production 2013 CX-5 2.0-liter cars (automatics built before 6 September 2012 without a kickdown switch, manuals before 15 November 2012): "Due to improper PCM control logic, the fuel injection amount may be improperly compensated when the engine start is not smooth and due to low quality fuel." The code "normally occurs during the fast idle immediately after starting the engine or after the fast idle lowers to a normal idle." The bulletin excludes cars whose short- plus long-term trims exceed 20 percent, says "It is not necessary to order a PCM part for this repair procedure," and covers the 0.4-hour reprogram under "Fed. Emission Warranty (long term)."

🟢 Nissan's NTB15-115 for the 2015 Altima 2.5-liter is written for a car where "There are no drivability issues," and its fix is a reprogram plus a new A/F sensor, in a set order: "CAUTION: The ECM must be reprogrammed (if it applies) before the A/F sensor is" replaced. 🟢 Ford's TSB 21-2443 for 2019-2020 F-150 5.0-liter flex-fuel trucks: "This may be due to software parameters in the powertrain control module (PCM)." 🟢 Isuzu's SB21-J-001 is the bluntest: "An investigation of returned fuel injectors has shown that injectors are being" replaced unnecessarily, and the analysis "determined the injectors were not the cause of this DTC setting." The fix, once normal diagnosis finds no mechanical fault, is a 0.3-hour recalibration. 🟢 And four Toyota and Lexus Tech Tips from 2015-2019 warn that the scan tool's own injection-mode test could store P0172 on certain models — a code a technician can create while testing.

Software inside the Honda 1.5-liter campaign. 🟢 The 2019 bulletins update the engine and transmission software on 2016-2018 Civic and 2017-2018 CR-V 1.5-liter cars, and say "The ECU and TCM software is covered under the vehicle's emissions warranty beyond 6 years." The 19-032 CR-V owner letter puts a number on it: 8 years or 80,000 miles from the original sale date.

What the owners report. A 2017 CR-V owner: "Honda tech performed 19-032 procedure and cleared the warning light. Three weeks later the warning light appeared again." A 2018 CR-V owner's repair order lists the software update, the A/C control unit and the oil change under 19-032, and a few days later a quote of $1,300 for four injectors. Software fixed the first version of the problem on many of these cars and not the later one — which is Route 4.

The cheap cause that gets skipped. The calibration ID. A dealer can compare it with the latest in minutes, and on the Accord 2.0-liter the whole repair is the update.

Fix it yourself — what to write down. When the code set: first start of a cold morning, after a short trip, after a fill-up, or on a warm engine at idle. A code that appears only on cold starts is pointing at software or fuel in the oil, not at a failed part.

At the shop — say this: "Is there a software update or bulletin for P0172 on my VIN, and is my engine computer on the latest calibration? The code sets on cold mornings — can we update before replacing anything?"

Route 3 · Air and ethanol the computer did not count — $0 to $400

If air the computer counted never reaches the cylinders, or the computer believes the tank holds different fuel than it does, the mixture reads rich without any extra fuel at all.

What the documents show — the GM 1.5-liter duct. 🟢 GM's emission recall N192271200, December 2019, for about 170,000 US 2019 Equinox, Malibu and Terrain models with the 1.5-liter turbo: "Under certain conditions the engine intake charge air cooler outlet duct may become disconnected from the throttle body when turbo boost is active." The codes it names are "P0172 (Fuel Trim System Rich), P0299 (Engine Underboost), P0101 (Mass Air Flow (MAF) Sensor Performance), P1101 (Intake Air Flow System Performance), or P0506 (Idle Speed Low)," and the risk it names is plain: "When the vehicle reaches low speed or idle, the engine could stall." The fix is an improved retainer, a 0.2-hour job, and the coverage has no end: "Dealers are to service all vehicles subject to this recall at no charge to customers, regardless of mileage, age of vehicle, or ownership, from this time forward." In California, "Uncorrected emission recalls will result in the inability to renew your California vehicle registration." 🟢 For 2018-2022 Equinox, Malibu and Terrain 1.5-liter models, GM's 22-NA-224 (November 2022) has technicians check whether the duct has come off, inspect the tube, clip and throttle body and replace only what is damaged — under the powertrain warranty rather than free like the recall — and warns: "The throttle body and mass airflow (MAF) sensor associated with the listed codes should only be replaced if they are damaged or found to be the cause of the code." Our P0101 guide covers the same recall from the airflow side.

What the documents show — ethanol. A flex-fuel engine estimates how much ethanol is in the tank and adds fuel for it. If the estimate is too high, it adds too much. 🟢 Ford's SSM 48573 for 2018-2020 F-150 5.0-liter flex-fuel trucks traces P0172 and its siblings to "incorrect flex fuel learning, which is often caused by customer refueling habits or a stuck open evaporative emissions purge valve." Its successor, SSM 49050, narrows the habit to "adding only small amounts of fuel" and names "a component concern" in place of the purge valve. 🟢 Toyota's T-SB-0166-19 for 2009-2019 Tundra and 2009-2018 Sequoia with the 5.7-liter flex-fuel engine: "Techstream Data List analysis may reveal negative fuel trims and an elevated alcohol density estimate relative to the vehicle's actual fuel alcohol content." It qualifies a truck at fuel trim of minus 10 percent or lower, or an alcohol estimate of 15 percent or more on E0-E10 fuel, then reprograms the computer and replaces the fuel pump, 2.2 hours under the "Toyota Federal Emission Warranty," 96 months or 80,000 miles from the in-service date. 🟢 GM's PIP4792D describes the same mislearn on E85 V8 trucks and reflashes when the computer's ethanol reading and a tested fuel sample disagree by 17 percent or more.

What the owners report. A 2020 Avalon owner lists P0172 among lean codes, purge and evaporative codes, and an engine that stalled after a fill-up. No 2019 GM 1.5-liter car appears among the 87, and none of the flex-fuel trucks the bulletins describe. Two other complaints stay unresolved: a 2013 CX-5 owner saw P0172 with a downstream oxygen sensor code and then two stalls right after stopping, and a 2019 Stinger owner's P0172 came with a limp mode a dealer first blamed on a loose wire connection before it returned.

The cheap cause that gets skipped. The duct and the receipt. On the GM 1.5-liter the answer is a clip and a VIN lookup; on a flex-fuel truck it is what went into the tank at the last two stops. Neither is a part number from a generic code list.

At the shop — say this: "Can you check my VIN for emission recall N192271200, and confirm the charge-air duct is seated before replacing the airflow sensor? On a flex-fuel truck, can you compare the computer's ethanol estimate with a fuel sample and check the purge valve?"

Route 4 · The injectors — $350 each to $2,300 for a replacement

A leaking or sticking injector adds fuel the computer never commanded, and on direct-injection engines, fuel that drips into a cylinder after shutdown ends up in the oil too.

What the documents show — Honda. 🟢 From June 2021 to October 2023, Honda sent dealers 26 requests for parts, most valid for two weeks, and we went through all of them. They came in waves: 2018-2021 Accord 1.5-liter, Civic Si and CR-V models first; then Accords and CR-Vs, with Accords limited from September 2021 to cars built after May 2018; Accords alone in February 2022; 2019-2022 Accords and 2020-2022 CR-Vs, non-hybrid, in mid-2022; and 2019-2020 Accords, Civic Sis and CR-Vs in 2023. Every one required misfire codes or P0172, a problem where the "Issue has been traced to the fuel injectors using the iN troubleshooting procedure" — in 2023, "according to iN procedure" — and no repair yet, because "To better understand the cause of this condition, AHM would like to collect specific parts from the vehicle prior to you attempting a repair of any kind." From mid-2022 they also required that "Fuel injectors & the high-pressure fuel pump have not been replaced previously." None offers a repair or coverage; together they show Honda examining injectors from these engines for more than two years. 🟢 For the 2015-2016 Fit, 22-002 goes further: "Certain fuel injectors may not have been installed to proper specifications," and for P0172 the procedure is short — "P0171 or P0172 - Go to REPAIR PROCEDURE." — with coverage that is "10 years from the original date of purchase or 150,000 miles, whichever comes first." 🟢 Honda's 20-100 and 21-010 extend injector repairs on 2016-2019 Pilot, 2017-2019 Ridgeline and 2018-2019 Odyssey V6 engines to the same 10 years or 150,000 miles, blaming "debris from the high pressure pump or the fuel injector machining process" — but those bulletins list catalyst, misfire and air-fuel imbalance codes (P219A/B), not P0172. 🟢 25-044 gives the repair for leaking injectors on 2023-2024 and early-2025 CR-V and Accord Hybrids, where P0172 can appear alongside heater codes.

What the documents show — others. 🟢 Ford's 18-2310 and its successor 20-2324, for 2018 F-150 2.7-liter trucks (20-2324 adds a PCM reprogram and keeps the injector test for trucks built before 12 July 2018), give a test anyone can understand: "Shut off the engine and monitor the fuel rail pressure. Does the fuel rail pressure drop below 6.9 kPa (10 PSI)" within 30 seconds; "Yes - replace the direct injection fuel injectors." And against all of that, GM's 2.0-liter bulletins and Isuzu's diesel bulletin are the reminder that new injectors will not fix a P0172 that comes from fuel in the oil or from software.

What the owners report. In 45 of the 87 complaints, injectors were diagnosed, replaced or recommended, 44 of them on Hondas and 36 on CR-Vs. Owners report quotes and bills of $1,300 to $2,300 for injector work, a median of $1,689 across eleven figures. A 2017 CR-V owner's dealer called the injectors "faulty" and "from a bad batch." Several describe injectors on back order with no date. A 2019 CR-V owner paid about $1,790 and writes that the warning lights came back. A 2018 CR-V owner has "replaced the fuel injectors twice after completing the recalled fuel pump." And a 2017 CR-V owner reports the dealer and Honda refusing to replace the high-pressure fuel joint pipe with the injectors, which the owner describes as a one-time-use part.

The cheap cause that gets skipped. The cylinder test. Honda's V6 bulletins run a cylinder air-fuel test only when a catalyst code appears alone and otherwise go straight to new injectors; the Fit bulletin swaps coils and plugs for misfire codes, tests cylinders only for P219A or P0420 alone — and for P0172 goes straight to the repair. Ford's pressure-drop test after shutdown is pass or fail for the whole rail, and a failure means all six injectors. Dealers in these complaints report cylinder air-fuel tests on 1.5-liter CR-Vs — one naming cylinders 1, 2 and 3 as rich, another failing all four. On those engines, where no bulletin prescribes a repair, a set replaced without that result in writing is a guess at a four-figure price.

Fix it yourself — the honest split. Recording the codes, freeze frame and fuel trims, and asking for the test results in writing, are owner jobs. Direct injectors are not: they run at pressures our injector guide puts in the thousands of psi, and their seals and lines are specified by the maker.

At the shop — say this: "Which cylinders failed the air-fuel or pressure-drop test? Is my VIN covered by 22-002, 20-100 or 21-010, or included in a Honda parts request? If you replace the injectors, will you replace the seals and the fuel joint pipe, as the dealer in one of these complaints recommended?"

Route 5 · Fuel pumps, fuel pressure and the engine behind the code — $0 to $7,650

The high-pressure pump on a direct-injection engine sits on the engine and is driven by it. When its seal wears, fuel can leak into the oil; when its valve sticks, pressure goes where it should not.

What the documents show. 🟢 Kia's recall 23V-634, for 2018-2021 Stinger 2.0-liter turbo models: "The fuel control valve plunger may stick inside the high-pressure fuel pump, causing over-pressurization and loss of drive power." Dealers inspect and, if needed, replace the pump and update the engine software for free, and owners who already paid can apply for reimbursement. The recall names no code; two Stinger owners in this file report P0172. 🟢 GM's special coverage 12313, July 2013, for the 2.4-liter engine in 2010-2011 LaCrosse, Equinox and Terrain and the 2011 Regal: "In addition, the fuel pump plunger shaft seal may wear and allow fuel to leak into the crankcase, setting a P0172 DTC, and illuminating the Malfunction Indicator Light." It covered the pump and balance chain for 10 years or 120,000 miles from the in-service date — past now for nearly every car. 🟢 GM's PIP6113, May 2026, adds a newer twist for GM 2.4-liter engines (and the 2.0-liter in the Regal and Verano) from 2010-2017 that stall at a stop with P0191, occasionally with P0172: "When normal diagnosis of the DTC's does not lead to a solution, inspect the markings on the body of the high pressure fuel pump to verify the high pressure fuel pump is an original manufacture part." 🟢 Mercedes-Benz's LI07.70-P-078520 for the M254 four-cylinder traces limp mode, low rail pressure and P017200 to "Gas bubbles forming in low pressure fuel system due to fuel boiling," fixed with software — "Do not replace hardware unless clear part malfunction is determined." 🟢 And Honda's recall 23V-858 replaces the in-tank fuel pump module, whose impeller can deform (NHTSA's record: about 2.5 million 2013-2023 vehicles); owners in this file describe P0172 and injector work around that recall, but the recall itself names no code.

What the owners report. A 2016 Sorento owner's dealer said the fuel pump and lines were "LEAKING FUEL INTO THE ENGINE" and the oil was diluted, with the pump covered under warranty and the oil change not. A 2017 Sorento owner at 65,000 miles was told "gas was getting into the oil" and a new high-pressure pump was needed. A 2015 Equinox owner at 197,000 miles was told the high-pressure pump had failed and "fuel had leaked into the engine through the PCP valve." Three owners tie P0172 to recent recall work: a 2018 Accord owner whose dealer "admitted the O-ring was misinstalled" during the fuel pump recall and charged $425, a 2018 Civic Si owner, and a 2018 CR-V owner. At the far end, 5 of the 87 describe engine damage — a 2013 F-150 with half its cylinders at zero compression and a $7,650 engine, a 2019 Sportage with pistons the dealer called "melted" and a $6,700 quote, and a 2021 Soul under Kia's piston-ring recall.

The cheap cause that gets skipped. The VIN, and the part number on the pump. A Stinger under 23V-634 is a free repair; on a GM 2.4-liter that stalls with P0191, GM tells dealers to check the pump's markings for a non-original part when normal diagnosis finds nothing.

At the shop — say this: "Is my VIN under recall 23V-634 or any fuel pump recall? Is the high-pressure pump original? Before any engine work, can you record the oil level and fuel smell, and tell me in writing what the compression test showed?"

The Honda file: one engine, three stories, and which coverage is still running

Hondas are 63 of the 87 complaints that name P0172, and the documents behind them tell three different stories that owners and even dealers tend to merge into one.

Story one, 2019: software and fuel in the oil on 2016-2018 Civic and 2017-2018 CR-V 1.5-liter engines. 🟢 Product updates 18-114, 18-124, 18-137 and 19-025 to 19-027 changed engine and transmission software, changed the oil and reprogrammed or replaced the A/C control unit; from March 2019 the A/C-unit updates 18-114 and 18-137 were limited to cars located or registered in 21 cold-weather states; dealers elsewhere used 19-026 or 19-027, which need Honda's approval. 🟢 The warranty extensions 19-032, 19-033, 19-037 and 19-038 then extended coverage on camshafts, rocker arms and spark plugs "from the original 5 years/ 60,000 miles to 6 years with unlimited mileage from the original sale date." One clause in all four extension bulletins explains much of what came later: if the codes return after the spark plugs are replaced, "this bulletin does not apply."

Story two, 2021-2023: injectors on 1.5-liter engines. The 26 parts requests in Route 4 reached Accords, 2019-2022 CR-Vs and 2019-2021 Civic Sis that the 2018-2019 campaign did not cover, as well as 2018 CR-Vs and 2018 Civic Sis that it did. They accepted only cars where the dealer had traced the problem to the injectors, offered no repair program, and the last expired in October 2023.

Story three: separate injector programs on other engines. The 2015-2016 Fit (22-002), the V6 Pilot, Ridgeline and Odyssey (20-100, 21-010), and the 2023-2024 and early-2025 hybrids (25-044).

The status column is our reading of each document's own terms against September 2026, not a statement from Honda; the VIN decides. Two things are worth knowing before you call. The two Civic owner letters for the same campaign give different software coverage — 8 years or 80,000 miles in one, 15 years or 150,000 miles in the other — and neither says which owners received which; bulletin 19-038 mentions spark plugs covered beyond six years "in certain states." And the first version of 19-037 (April 2019) listed the covered parts as a closed set, while 19-032 in its June 2019 version, and the later versions of the others, extend coverage to "any engine components, such as" camshafts and rocker arms.

The 2019 CR-V gap. The 2018-2019 campaign covered 2017-2018 CR-Vs; 8 of the 50 CR-V complaints are 2019 models, and a 2019 owner writes that the same problem "was not included for my 2019 model year even though it's the same 1.5L Turbo motor." Honda's 2021 parts requests named 2018-2021 CR-Vs, and the 2023 requests included 2019 CR-Vs with VINs after 7FARW2…KE056667. Our CR-V guide covers the oil-dilution settlement that ran beside the 2018-2019 campaign.

When every warning light comes on

41 of the 87 owners describe several warning lights or messages at once, 37 of them CR-V owners. A 2017 CR-V complaint lists them: "Emission System Problem, Brake System Problem, Brake Hold System Problem, Power Steering System (EPS) Problem, Vehicle Stability Assist (VSA) Problem), Hill Start Assist Problem, Adaptive Cruise Control Problem, Collision Mitigation System Problem, Road Departure Mitigation System Problem, Electric Parking Brake Problem, Tire Pressure Monitor Problem." Owners describe driver-assist systems switching off while the messages are shown, and two describe near misses caused by the alarm as much as by the car.

No Honda document we went through explains why an engine fault lights up the brake, steering and driver-assist messages. In the 41 complaints that describe the cascade, P0172 was read alongside it, often with misfire codes — though a file chosen because it names P0172 cannot say how often another code sits underneath. Treat the cascade as an engine diagnosis to book this week, not as a dozen separate failures, and write down every message before you clear anything.

What 87 complaints naming P0172 show

We went through every complaint in NHTSA's file that names P0172, and sorted all 87 a second time, independently, by the same written rules. The two sortings matched on the category for 79 of 87, or 91%; the 15 complaints with any difference — 8 on the category, 7 on a flag — were settled by the written rules and are marked in the published file.

By maker and model. Honda 63 — CR-V 50, Accord 5, Civic 3, Pilot 3, Fit 2 — then Kia 10, Chevrolet 4, and one or two each from eight other makers. The CR-Vs are 2017 (28), 2018 (13), 2019 (8) and one 2016.

By year received. 1 in 2018, 4 in 2019, 1 in 2020, 9 in 2021, 4 in 2022, then 16, 16 and 15 in 2023-2025, and 21 in 2026 by 21 September.

Stalls. 31 of the 87 describe a stall, a limp mode or a marked loss of power.

The honest limits. Complaints over-represent frightening failures, and owners write down the dealer's diagnosis as they heard it. Sorting every complaint twice reduces sorting error; it does not verify a repair.

What owners say they paid, by lane

Twenty-two figures from the 87 complaints, each read in context and published with ODI numbers. They are bills, quotes and estimates as owners reported them, not invoices.

Three figures explain the spread. The $1,507.08 a 2017 CR-V owner was quoted for injectors a month after the dealer did the 19-032 repair under the extension — "THEY SHOULD HAVE REPLACED THE INJECTORS FROM THE START." The $1,058.58 a 2020 Accord owner was offered as their share under a one-time goodwill arrangement, and declined. And the $90 spark plugs a 2021 Civic owner bought three times: even after the whole injector system was replaced, a fresh set was "charred" by the end of the same day.

Why P0172 comes back after new injectors

Why does P0172 come back after new injectors, and what should be checked before a second set? Often because the injectors were not the only source of fuel. GM's bulletins for its 2.0-liter turbo say replacing the pump or injectors will not correct P0172 caused by fuel collecting in the crankcase, and Isuzu found that the injectors it got back were not what set the P0172. Fuel already in the oil keeps reaching the intake through the crankcase ventilation until the oil is changed and the short-trip pattern changes. In PulsCar's review of the 87 federal complaints, owners also describe new injectors followed by the same warning lights, and injectors replaced twice around a fuel-pump recall. Before a second set, ask for the oil to be checked for fuel, a cylinder-by-cylinder test showing which injectors leak, the software level, and whether the high-pressure pump and its seals were inspected.

Can you drive with P0172?

Briefly, sometimes. It depends on the smell, the oil and the dash.

P0172 alone, engine smooth, no fuel smell, oil level normal. Drive it to a shop within days, and avoid a week of short trips.

P0172 with a rising oil level or oil that smells of fuel. Change the oil before driving much further; diluted oil protects the engine less.

P0172 with misfires, a flashing light, or loss of power. Keep trips short and gentle, and have it seen this week; a flashing light means a misfire that can damage the catalytic converter.

Any fuel smell, or a stall at idle. Stop driving it. On a 2019 GM 1.5-liter turbo, check the free recall first.

Can you drive with a P0172 code, and when should you stop? Sometimes briefly: if the engine runs smoothly, there is no fuel smell and the oil level has not risen, P0172 usually means wasted fuel and a failed emissions test rather than an immediate danger. In PulsCar's review of the 87 federal complaints that name the code, 31 owners describe a stall, a limp mode or a marked loss of power, and 41 describe several warning lights at once, most of them on 2017-2019 CR-Vs. Stop and have it checked the same day if you smell fuel, the check engine light flashes, the engine misfires, or it stalls at idle — GM's emission recall for 2019 Equinox, Malibu and Terrain 1.5-liter models names a stall at low speed as the risk. If the oil level has risen or smells of gasoline, change it before driving further.

Should you buy a used car with a P0172 history?

With the paperwork, yes. Ask for the repair orders: an oil change and a software update on a car driven on short trips, a bulletin number, or a documented injector test with the failed cylinders is a closed case; three rounds of spark plugs and a cleared code is not. Pull the dipstick on the lot and smell it. On a 2017-2019 CR-V or 1.5-liter Civic or Accord, ask a dealer which Honda campaigns show as completed on the VIN, and whether injectors were ever replaced. On a 2019 Equinox, Malibu or Terrain 1.5-liter, confirm emission recall N192271200 is done — in California, the registration depends on it.

Clearing P0172 before an inspection

Clearing the code turns off the light and resets the readiness monitors, and the fuel system monitor relearns quickly: if the cause is still there, P0172 usually returns within a few drives, and an inspection station will see monitors that are not ready. Fix the cause — oil, software, air duct, injector or pump — drive until the monitors report ready, and keep the repair order. A code caused by short trips can pass a test after an oil change and a long drive and return by the next winter.

What a shop actually does with a P0172, checkpoint by checkpoint

1. Checks the oil for level against the last change and for a fuel smell.
2. Reads every code and the freeze frame, noting misfire, imbalance, airflow, boost and fuel pressure codes.
3. Checks the VIN for recalls, emission recalls, warranty extensions and parts requests.
4. Reads the fuel trims, warm and at idle, and repeats GM's test with the airflow sensor unplugged where it applies.
5. Checks software level against the latest calibration.
6. Inspects the air path for a loose charge-air duct, intake leaks after the airflow sensor and a stuck purge valve.
7. Tests the injectors cylinder by cylinder and the fuel pressure, including the drop after shutdown.
8. Replaces only what failed, then changes the oil if fuel was in it, and confirms the trims have returned to normal.

Three P0172 traps that cost owners the most

Trap 1: injectors into diluted oil. New injectors do not remove fuel already in the crankcase, and GM says in writing that they will not fix fuel-in-oil P0172. Lesson: dipstick and oil change first, and a cylinder test before a set.

Trap 2: the airflow sensor as the answer. On the GM 1.5-liter turbo, P0172 with P0101 often means a detached duct — a free recall on 2019 models; GM tells dealers the airflow sensor should be replaced only if it is damaged or proven to be the cause. Lesson: check the duct and the VIN before the sensor.

Trap 3: a program you do not know about. Kia's Stinger recall and Honda's 1.5-liter programs reach cars whose owners in this file did not mention them, and GM's 1.5-liter recall does not show up in the complaints at all. Lesson: ask for emission recalls and warranty extensions by name, not only safety recalls.

Three P0172 quotes, decoded

These are composite scenarios, not individual customers: each combines details that come up repeatedly in owner reports and shop quotes; the dollar figures are drawn from the ranges on the price ladder above.

Scenario 1: 2019 Chevrolet Equinox 1.5T, 88,000 miles, stalls at a light with P0172 and P0101, quote for an airflow sensor. A second dealer finds the charge-air duct off the throttle body and the VIN open under N192271200. The retainer is fitted for free. Lesson: on this engine, the free recall comes before any sensor.

Scenario 2: 2017 Honda CR-V EX, 96,000 miles, every warning light on, P0172 and P0303, quote for a full injector set. The owner asks for the cylinder test in writing and the VIN history; the 2018-2019 campaign was done, the six-year extension has ended, and cylinder 3 fails. The injectors are replaced at a price within the owners' $1,300-$2,300 range, and the oil is changed. Lesson: the test and the VIN history decide the bill, even when they do not reduce it.

Scenario 3: 2016 Chevrolet Malibu 2.0T, 61,000 miles, P0172 every winter, quote for a high-pressure pump. The oil is over the full mark and smells of fuel; the owner's trips are ten minutes each way. An oil change, a PCV valve per GM's bulletin and a software update clear it, and the owner adds a long drive every weekend. Lesson: on a short-trip car, the calendar is the cause.

The P0172 plan: 10 minutes, today, this week

In the next 10 minutes: pull the dipstick and smell it; read every code and the freeze frame; note every dash message; and if you smell fuel or the light flashes, stop.

Today: run the VIN at nhtsa.gov/recalls and ask a dealer about emission recalls, extensions and parts requests by name — N192271200 on a 2019 GM 1.5-liter, 23V-634 on a Stinger, the 2018-2019 campaign, 22-002 or 20-100/21-010 on a Honda. Find your last oil-change receipt.

This week: change the oil if it smells of fuel; ask for fuel trims, a software check and a cylinder test before injectors are ordered; and get any coverage answer in writing.

If you are not sure whether what you hear is a misfire or something else, PulsCar's free sound check screens a 30-second recording of your engine. It does not read codes; it is a second opinion on what the engine 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. Honda service bulletins 18-114 (versions 4 and 7), 18-124, 18-137 (versions 2 and 9), 18-147, 19-012, 19-025, 19-026, 19-027, 19-032 (versions 3 and 4), 19-033, 19-037 (versions 1 and 5), 19-038; five owner letters of July 2019; dealer message of 5 April 2019 announcing the extension.
2. Honda 22-002 and its dealer message; 20-100, 21-010, their owner letters and dealer message; 23-026 (versions 1 and 2); 25-044; 26 parts-request dealer messages, June 2021 to October 2023; 19-072. Acura 23-010.
3. GM 18-NA-246, 22-NA-056, PIP5651 and PIP5651G, PIP5710 and PIP5710A, PIE0569 and PIE0569B, service update N192266090, emission recall N192271200, 22-NA-224, special coverage 12313, 12313A and 12313B, PIP4792D, PIP4813B and PIP4813C, PIP5446 and PIP5446A, service update 18009, 22-NA-128, PIP6113, PIP6115.
4. Ford SSM 48573 and 49050; TSB 17-0014, 18-2310, 18-2321 (superseded by 19-2091, which we went through; NHTSA summary only, not counted in our list), 19-2091, 20-2324, 21-2083, 21-2154, 21-2443, 22-2393; owner letter 21L04 (does not name P0172).
5. Toyota and Lexus T-SB-0166-19 and its revision; T-SB-0058-13 and its revision (image PDFs; NHTSA summaries only); Tech Tips T-TT-0376-15, L-TT-0193-15, T-TT-0521-19, L-TT-0255-19.
6. Mazda SA-026/18 and 01-019/18. Nissan NTB15-115. Infiniti ITB11-054A. Isuzu SB21-J-001. Mercedes-Benz LI07.70-P-078520. Jeep and Ram PCM flash bulletins and STAR case S2118000013.
7. Recalls 23V-634 (Kia, Stinger; follow-up owner letter of 18 December 2023) and 23V-858 (Honda; owner letter of October 2024).
8. PulsCar analysis of NHTSA public data, September 2026: all 87 complaints naming P0172, sorted twice, independently; 22 owner-reported amounts; the document list with its review status. How we did it.

For the neighboring codes and symptoms: P0171, P0174, P0101, P0087, P0300 misfire, black smoke from the exhaust, car smells like gas and the code index. For the cars: Honda CR-V, Honda Civic, Honda Accord, Chevrolet Equinox, Chevrolet Malibu and Kia Sorento.

Methodology. The complaint set is every complaint in NHTSA's file whose narrative contains P0172; all 87 were gone through in full and sorted twice, independently, by the same written rules (the two sortings matched on 91%, 79 of 87), and differences were settled by those rules. Every complaint quoted, and every dollar figure, was checked in full. A search of NHTSA's recall file from 2010 for P0172 returns no campaigns. NHTSA's manufacturer-communications file runs from 2015; some documents in it are dated earlier. 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 117 documents gone through in full in our published list — among them Honda 19-032, 19-037, 22-002, 23-026 and all 26 parts requests, GM 18-NA-246, 22-NA-056 and emission recall N192271200, Mazda SA-026/18, Toyota T-SB-0166-19 and Kia's 23V-634 letter — were downloaded from static.nhtsa.gov and gone through in September 2026, when the complaint, recall and bulletin files behind our analysis were also queried.

Had a P0172 fixed by an oil change, a software update, a recall or an injector program — or refused one? Email [email protected] with the vehicle, mileage and outcome.