WenmarOpen by Wenmar Pro

Service bulletins for the 2021 GMC Sierra

A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.

1649 on file from NHTSA, as of 2026-10-19.

About P12A6 on the 2021 GMC Sierra: what the code means, and the bulletins and recalls about the same components.

By type

By component

By trouble code

By topic

Only bulletins with trouble code: P12A6 are shown. Show all

Bulletins, newest first
PIT6396A2025-08-22. Service bulletin. UNKNOWN OR OTHER. This PI communicates an issue with a SES MIL with DTC P2535, P12A6, P10DA and/or C111B maybe set after replacing the fuel pump driver module. Engineering is working on a fix, but in the meantime, dealers are to install a diode.
PIT63962025-06-29. Service bulletin. UNKNOWN OR OTHER. This PI communicates an issue with a SES MIL with DTC P2535, P12A6, P10DA and/or C111B maybe set after replacing the fuel pump driver module. Engineering is working on a fix, but in the meantime, dealers are to install a diode.
20-NA-2182022-06-02. Service bulletin. ENGINE AND ENGINE COOLING. This service bulletin provides repair information to correct a customer concern of Possible Crank No Start or Extended Crank with DTC P12A6.
20NA2182021-07-19. Service bulletin. ELECTRICAL SYSTEM. This service bulletin provides repair information to correct a customer concern of Possible Crank No Start or Extended Crank with DTC P12A6.
20NA2182021-07-06. Service bulletin. ENGINE AND ENGINE COOLING. This service bulletin provides repair information to correct a customer concern of Possible Crank No Start or Extended Crank with DTC P12A6.
20NA2182021-05-24. Service bulletin. POWER TRAIN. This service bulletin provides repair information to correct a customer concern of Possible Crank No Start or Extended Crank with DTC P12A6.

The summaries are NHTSA's. Each bulletin's page links NHTSA's copy of the manufacturer's document.