The problem: affected trucks may throw a falsely set fuel injector diagnostic trouble code of P026C and/or P20EE. This service update involves trucks equipped with the optional Duramax turbodiesel 6.6L L5P V8 engine only.
The hazards: while this issue does not pose any sort of safety hazard to the driver or vehicle occupants, owners will ideally want these diagnostic trouble codes cleared to prevent instrument panel warning lights or other future problems.
The fix: dealers will be instructed to reprogram the engine control module (ECM). This will clear the falsely set diagnostic trouble codes. No parts are required to perform this repair.
Affected components: engine control module (ECM).
- 2021 Chevy Silverado HD (with 6.6L L5P V8 Duramax engine only)
- 2021 GMC Sierra HD (with 6.6L L5P V8 Duramax engine only)
Number of affected vehicles: GM has not said how many 2021 Chevy Silverado HD and 2021 GMC Sierra HD trucks may be affected by this problem. This service update only involves Silverado HD and Sierra HD trucks that are currently in dealer inventory. The service update will expire on June 30th, 2022.
Owners should: owners of affected GM pickup trucks will be contacted by the automaker and instructed to make an appointment with their dealer. Concerned parties can also reach out to GM directly using the contact information included below with any questions or concerns they may have.
- GM service update number: N212336750
- Chevrolet Customer Service: 1-800-222-1020
- GMC Customer Service: 1-800-462-8782