Pulscar Check Engine Code Index 2026 — method Built 17 September 2026 from NHTSA's public technical service bulletin files. SOURCE https://static.nhtsa.gov/odi/ffdd/tsbs/TSBS_RECEIVED_2015-2019.zip, _2020-2024.zip, _2025-2026.zip Field dictionary: https://static.nhtsa.gov/odi/ffdd/tsbs/TSBS.txt Fields used: 4 TSB/Document ID, 5 Mfr Communication Date, 8 Make, 9 Model, 10 Model Year, 14 Summary. Complaint metrics: NHTSA ODI complaint flat files COMPLAINTS_RECEIVED_2015-2019/2020-2024/2025-2026, 777,040 distinct vehicle complaints (ODINO, product type V) received 1 Jan 2015 to 8 Sep 2026. WHICH BULLETINS COUNT 1. The Summary field contains the exact code (whole word, e.g. \bP0420\b). 2. Excluded makers: heavy-truck, bus, motorcycle and RV makers (Mack, Mack Trucks Inc., Volvo trucks, Volvo Bus, Hino, Kenworth, Peterbilt, Paccar, International, IC Bus, Freightliner, Western Star, Isuzu trucks, Blue Bird, Thomas Built, Navistar, Harley-Davidson, Indian, Triumph, Ducati, Kawasaki, Yamaha, Suzuki, BMW Motorrad, Polaris, Can-Am, Prevost, Workhorse, Spartan, Autocar, Forest River, Chalet, Bison). 3. Excluded documents (counts are distinct document IDs naming one of the 17 codes): - 205 helpline "analysis lists" and documents marked not applicable to US-market vehicles (Summary or ID contains "customer states", "analysis list", "VIN4APIN", "hotline list", "not applicable to vehicles built for the US", "not for US market", "built for the ... market"); - 138 Honda/Acura dealer messages, parts-collection requests and owner notification letters (Summary begins "Dealer message", "DLR MSG" or "Owner Notification Letter", or says "(AHM) is searching for" / "(AHM) is investigating"), unless the document ID is a numbered bulletin (NN-NNN). These announce, investigate or repeat a numbered bulletin and describe no repair of their own; counting them would double count Honda warranty extensions and inflate P0420, P0430, P0441 and P0087; - 11 entries whose document ID contains no digits (e.g. "Service Bulletin"), which cannot be de-duplicated reliably. 4. One bulletin = one manufacturer group + one normalized document ID. Groups: GM (Buick, Cadillac, Chevrolet, GMC, Pontiac, Saturn, Hummer, Saab, Oldsmobile, Geo, "General Motors"); Stellantis (Chrysler, Dodge, Jeep, Ram, Fiat, Alfa Romeo, "Alfa", SRT, Maserati, "FCA"); Ford (Ford, Lincoln, Mercury); Honda (Honda, Acura); Toyota (Toyota, Lexus, Scion); Nissan (Nissan, Infiniti); Hyundai (Hyundai, Genesis); VW Group (Volkswagen, Audi, Bentley, Lamborghini); JLR (Jaguar, Land Rover); other makes stand alone. Normalization: remove spaces; a leading "TSB"/"SB"/"SSM"; a trailing "BULLETIN" word; trailing revision marks (REV A, REV-C, Rev. B, R1, _TSB); a version suffix _1.._99 after digits (Volkswagen TSB_2079209_1/_2/_3); a single trailing revision letter after digits (PIP5110C -> PIP5110); hyphens. For Honda group only, a leading WE/WEA/A/B before a 4-5 digit number is removed (A13-078 and WE - A13-078 are one bulletin). 5. Result: 2,151 code-bulletin pairs, 1,412 distinct bulletins, 15 manufacturer groups. Latest communication date: 31 August 2026. SOFTWARE UPDATE (lower bound) A bulletin is flagged when its Summary matches: re-?program | re-?flash | begins with "Flash:" | software (update|upgrade|logic) | update the PCM/ECM/ECU/TCM/ISCM | calibration (update|change) | logic (improvement|revision|update) | ECU upgrade | ECM upgrade | with the latest (available) software | software in the PCM/ECM | due to (the) software | software parameters Audit, flagged: 30 random flagged bulletins (10 Stellantis, 20 other), full Summary text read: 28 plainly describe a software or calibration update; 2 (Nissan NTB22-067, Nissan ITB19-010) make reprogramming conditional on a part number or calibration table check. Audit, not flagged: 40 random unflagged bulletins read: 2 clearly describe a software update (Kia SC114 "update the Engine Control Unit", GM PIP5905 "updated Engine Control Module calibrations"); 14 do not state the remedy in the Summary; the rest describe parts, inspections, cleaning or procedures. Other known misses: Ford TSB 25-2133, Volkswagen 01-21-02, GM 22-NA-054. The share is therefore a floor. Stellantis publishes many separate flash bulletins, often listing dozens of codes; the index reports the software share both with and without Stellantis. COVERAGE OR EMISSIONS CAMPAIGN Summary matches: special coverage | warranty extension | extended/extending the warranty | emissions recall | emissions service campaign | voluntary emissions. Also a floor (GM special coverage N252508350, a thermostat coverage whose Summary names no code, is not counted). 27 distinct bulletins are flagged. WHAT THE INDEX IS NOT A bulletin count is a count of manufacturer communications, not a failure rate, not a reliability ranking and not a measure of how often a repair works. Remedy types other than software are not reported because Summary text alone did not classify them reliably (manual audit accuracy about 75%). LICENCE CC BY 4.0. Credit "Pulscar Check Engine Code Index" and link to https://www.pulscar.io/blog/check-engine-code-index