P1A21: owner reports and bulletins
Got P1A21 on your scanner? Tell the mechanic your year, make, model and any symptoms and you'll get the likely cause and what to check first. Ask about this code.
What owners report to NHTSA
6 complaints filed with NHTSA mention P1A21, 6 of them since 2015, across 2 different models. The component owners most often filed it under: power train.
Most-reported models
| Vehicle | Complaints | Model years reported |
|---|---|---|
| CHRYSLER PACIFICA | 5 | 2020, 2021 |
Manufacturer service bulletins that name P1A21
13 technical service bulletins and manufacturer communications filed with NHTSA mention P1A21, from 2 makes. A bulletin means the manufacturer has documented a known cause or a fix procedure for that model. Examples:
- JEEP WRANGLER (2022), bulletin 10225250: Flash: Battery Pack Control Module (BPCM) Diagnostic and System Updates This bulletin involves updating the BPCM with the latest available software. Customers may experience a false Malfunction Indicator Lamp (MIL) illum…
- FIAT 500E (2013, 2014, 2015, 2016), bulletin 10076284: SUBJECT: FLASH: Electric Vehicle Control Unit (EVCU) System Enhancements OVERVIEW: This bulletin involves updating the software in the EVCU. SYMPTOM/CONDITION: A small number of customers may experience a Malfunction Ind…
Sources: NHTSA Office of Defects Investigation complaint database and manufacturer communications file, snapshots September 2026. A complaint or bulletin that mentions a code is a report about that vehicle, not a statement that the code has one cause.