PULSCAR ANALYSIS — P0446 AND THE EVAP VENT SIDE IN NHTSA'S PUBLIC FILES
PulsCar analysis of NHTSA public data, September 2026.
License: CC BY 4.0. Attribution: "PulsCar analysis of NHTSA public data, September 2026."
Published alongside https://www.pulscar.io/blog/p0446-code

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Prepared 25 September 2026. Source data: NHTSA public flat files (complaints received 2015 to 21 September 2026, 780,071 records; manufacturer communications from January 2015; recalls from 2010) and documents downloaded from static.nhtsa.gov.

1. Complaints naming the code
   Case-insensitive search of complaint narratives for P0446 (also "P 0446", "P-0446"): 13 complaints in the whole file. All 13 read in full.
   The same search for neighbouring vent codes is in vent-codes-in-complaints.csv (P0447, P0448, P0449, P0498, P0499, P2421, P2422, P1449, P1450).

2. The vent-side search set (418 complaints)
   Full-text search (SQLite FTS5) for: "vent valve", "vent solenoid", "canister vent", "vent control", "vent shut", "canister close", "vent line", "vent hose", "vent tube", spider* with evap/canister/vent*, dust with canister, evap* with fill/shut-off wording, plus the 13 P0446 complaints.
   This is a SEARCH set, not a set of confirmed P0446 cases. Flags in p0446-vent-side-418-complaints-flags.csv are regular-expression flags on the narrative text.

3. Random 50, read in full
   Python random.sample(rows ordered by ODI number, 50) with random.seed(20260926). Every narrative read to its end and coded into one category (p0446-random-50-read.csv).
   Result: 17 of 50 matched the words but concern other systems (A/C and heater vent controls, differential and transmission vents, a PCV line, a crash). 33 concern the EVAP system or fuel-tank venting: 12 stalling or rough running after refuelling or from the canister, 8 a vent valve or vent blockage, 6 fuelling problems (nozzle shut-off, spit-back, cannot fill), 4 tank or vent-line leaks or tank deformation, 3 other or unclear. None of the 50 names P0446; codes named are P0499, P1449, P2421, P0447 and P0441.
   One reader, one pass, no second coder.

4. Owner-reported amounts
   Dollar figures within about 220 characters of vent, canister or solenoid wording were extracted, then every complaint behind a listed figure was read in full. Figures are what owners told NHTSA: bills, quotes and estimates, not invoices. See p0446-owner-reported-amounts.csv.

5. Documents
   p0446-recalls-extensions-bulletins.csv lists 39 documents or document sets; each marked "yes" was downloaded as PDF from static.nhtsa.gov (exact URL via api.nhtsa.gov/safetyIssues/byNhtsaId) and read in full on 25 September 2026. Recall owner letters and Part 573 reports come from the same API (filterValue=recalls).

Limits: complaints over-represent bad outcomes; codes are named by owners, often from memory; a vent code on one brand is a different number on another. Nothing here is a failure rate.