PULSCAR ANALYSIS — P0401 AND THE EGR SYSTEM 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/p0401-code ------------------------------------------------------------------------------ 0. WHAT THIS FILE ADDS, AND WHAT IT DOES NOT REPEAT ------------------------------------------------------------------------------ The Check Engine Code Index already counts the manufacturer bulletins that name P0401 (59 bulletins, 8 manufacturer groups, at least 56% software updates, Stellantis 28, Toyota 9, Ford 7, VW Group 5) and publishes its own method. https://www.pulscar.io/blog/check-engine-code-index Those figures are cited, not recomputed. This file adds the complaint side, the programs that pay, and what owners report paying. ------------------------------------------------------------------------------ 1. SOURCE FILES ------------------------------------------------------------------------------ NHTSA's published flat files, loaded into SQLite without modification: complaints (777,040 received 1 Jan 2015 - 8 Sep 2026), recalls, manufacturer communications, investigations. Primary documents read in full on 22 September 2026: Toyota Warranty Policy Bulletin POL16-04 (program ZF3), Hyundai 23-EE-009H, GM 18NA089. Statute: 42 U.S.C. 7541(i), read at law.cornell.edu on 22 September 2026. ------------------------------------------------------------------------------ 2. TWO COMPLAINT SETS ------------------------------------------------------------------------------ A. Complaints that name P0401 (text "p0401" or "p 0401", case-insensitive): 31. The Check Engine Code Index reports 29 by its own stricter method; the difference is two narratives that write the code with a trailing "00" (P040100) or a space. All 31 were read in full: p0401-31-complaints-read.csv. hybrid or extended-range 13 (Volt 9, Prius 2, Niro 2) modern gasoline 7 diesel 6 gasoline built before 2007 5 B. Complaints that mention the EGR system at all: regular expression \b(EGR|exhaust gas recirculation)\b, re.IGNORECASE, after removing the abbreviation "e.g." which otherwise matches: 1,053 complaints. 30 random complaints (seed 2026) read in full: 26 on topic, 1 an owner's guess, 3 incidental mentions in a list. egr-30-complaints-read.csv. Flags for set B against all 777,040 complaints (egr-complaint-set-summary.csv): fire 4.65% (all complaints 1.82%) towed 4.65% (all complaints 5.11%) crash 0.95% (all complaints 4.37%) The fire excess is concentrated: Ram 1500 29 fire-flagged complaints, BMW 328d 6, Jeep Grand Cherokee 5 — the diesel EGR cooler recalls. A trap worth recording: a first recall query with SQLite LIKE '%EGR%' returned Takata airbag inflator recalls, because LIKE is case-insensitive and "egr" occurs inside "degradation" and "integral". Every EGR query here uses a word-boundary regular expression. ------------------------------------------------------------------------------ 3. OWNER-REPORTED AMOUNTS (egr-owner-reported-amounts.csv) ------------------------------------------------------------------------------ Dollar figures $100-$15,000 within about 120 characters of an EGR or cooler word and a repair word, excluding loans, purchase prices, trade value, deductibles, towing and rentals: 63 candidates, each read by hand; 40 published in lanes. Headlines: Chevrolet Volt EGR valve 11 median $2,800, range $1,100-$4,000 EGR valve, other gasoline 5 median $500 EGR cooler, gasoline 7 median $2,000 (six are 2019 Ford Edge) EGR cooler or system, diesel 8 mostly $1,800-$3,459 Not invoices; complaints over-represent bad outcomes. ------------------------------------------------------------------------------ 4. RECALLS AND PROGRAMS ------------------------------------------------------------------------------ egr-recalls.csv: 15 recall campaigns whose defect text names EGR, word-boundary matched. egr-programs-and-bulletins.csv: 15 manufacturer programs, warranty extensions and repair bulletins, each with its NHTSA document id. ------------------------------------------------------------------------------ 5. THE WARRANTY LAW, QUOTED ------------------------------------------------------------------------------ 42 U.S.C. 7541(i)(1): for light-duty vehicles from model year 1995 the emissions warranty period is "the first 2 years or 24,000 miles of use". 7541(i)(2): 8 years or 80,000 miles applies only to a "specified major emission control component", defined as "only a catalytic converter, an electronic emissions control unit, and an onboard emissions diagnostic device". An EGR valve is not on that list. Longer state coverage can apply; Toyota's ZF3 bulletin states 15 years or 150,000 miles for California-certified Prius in named states. ------------------------------------------------------------------------------ CASE SENSITIVITY ------------------------------------------------------------------------------ NHTSA stores complaint narratives in ALL CAPS through roughly 2020 and in mixed case from 2021. Every text query here is case-insensitive (Python re.IGNORECASE or SQLite LIKE). Note the flip side recorded in section 2: case-insensitive LIKE on a three-letter acronym also matches inside other words, so acronyms are matched with word boundaries.