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.

By type

By component

By trouble code

By topic

Bulletins, newest first
PIE05902020-12-07. Service bulletin. ENGINE AND ENGINE COOLING. This engineering information (EI) is requesting information from technicians to perform the check list provided and contact the engineer listed in regards check to the engine lamp being illuminated on the drivers information center (DIC).
1308116001F2020-12-07. Service bulletin. EQUIPMENT; ELECTRICAL SYSTEM; POWER TRAIN:AUTOMATIC TRANSMISSION. The intent of this technical bulletin is to identify aftermarket ALDL or DLC interface devices as potential sources for causing multiple customer concerns that do not have other diagnostic methods to identify them.
060089026Q2020-12-07. Service bulletin. EQUIPMENT. This warranty administration bulletin provides information on Warranty Administration - Customer Concern Not Duplicated (CCND) Labor Operation Numbers.
050604022R2020-12-07. Service bulletin. FUEL SYSTEM, DIESEL. This bulletin provides information on the TOP TIER Detergent Gasoline Licensed Brands and the TOP TIER Diesel Fuel Licensed Brands that are recommended for use in all GM vehicles and the TOP TIER FUELS website URL.
20NA1962020-11-30. Service bulletin. ELECTRICAL SYSTEM. This service bulletin provides information and a service procedure for dealers/technicians on OnStar Over the Air Update for TTY / TDD Operation and Continuous Improvement Changes.
20NA1602020-11-30. Service bulletin. EQUIPMENT:ELECTRICAL. This service bulletin provides information for dealers/technicians on Normal Characteristic - Wireless Phone Projection Audio Cuts Out Every 10 Seconds on New/Unsold Vehicles.
20NA0432020-11-30. Service bulletin. EQUIPMENT; ELECTRICAL SYSTEM. This informational bulletin advises the technician to not replace the TMAP sensor, clean it using air or harsh chemicals but allow time for the sensor to thaw.
19NA2372020-11-30. Service bulletin. FUEL SYSTEM, DIESEL; EQUIPMENT. This informational bulletin explains how to identify possible DEF contamination.
19NA1872020-11-30. Service bulletin. ENGINE; POWER TRAIN; EQUIPMENT. This bulletin provides additional information on how to graph a cylinder misfire and a possible diagnostic cause.
20NA1102020-11-30. Service bulletin. FUEL SYSTEM, DIESEL; FUEL SYSTEM, DIESEL:DELIVERY:FUEL PUMP. This informational bulletin advises the technician on what to do if the DEF pump has been replaced and perform a leak test to prime the pump.
18NA3612020-11-30. Service bulletin. FUEL SYSTEM, DIESEL; ENGINE AND ENGINE COOLING:ENGINE:DIESEL. This technical bulletin provides a procedure to flush the cooler lines to validate if there is excessive debris in the fuel system caused by a failed part.
18NA1502020-11-30. Service bulletin. ENGINE AND ENGINE COOLING; FUEL SYSTEM, OTHER. This informational bulletin provides information on 6.6L Duramax Possible Oil Leak Path Information.
18NA1032020-11-30. Service bulletin. FUEL SYSTEM, GASOLINE; ENGINE AND ENGINE COOLING:COOLING SYSTEM:PUMP. This service bulletin provides information to correct a customer concern of an in-tank fuel pump whining noise, engine hard to start and/or stalls and Malfunction Indicator Lamp (MIL) is illuminated.
17NA3932020-11-30. Service bulletin. EQUIPMENT ADAPTIVE/MOBILITY; EQUIPMENT; ENGINE. This informational bulletin explains how to check the NOx Catalyst Reductant-Load Adaptive Values using GSD2.
16NA3802020-11-30. Service bulletin. ENGINE AND ENGINE COOLING:EXHAUST SYSTEM:MANIFOLD/HEADER/MUFFLER/TAIL PIPE; EQUIPMENT; EQUIPMENT ADAPTIVE/MOBILITY. This informational bulletin provides a procedure on how to perform a quick test to check if the DPF is the cause of excessive soot from the tailpipe.
16NA3762020-11-30. Service bulletin. ENGINE AND ENGINE COOLING:ENGINE:DIESEL; FUEL SYSTEM, DIESEL. This informational bulletin provides information on higher than expected oil consumption.
16NA3722020-11-30. Service bulletin. EQUIPMENT; ENGINE AND ENGINE COOLING:ENGINE:DIESEL; FUEL SYSTEM, DIESEL. This bulletin provides information on common diesel engine tick noises and how they are considered part of normal operation and no parts should be replaced for these normal operating conditions.
16NA2442020-11-30. Service bulletin. EQUIPMENT; FUEL SYSTEM, DIESEL. This informational bulletin provides information on Diesel Exhaust Fluid (DEF) and the proper use of the DEF system.
16NA2222020-11-30. Service bulletin. ENGINE. This bulletin provides information on Engine Concerns that could result from lack of scheduled maintenance, improper service or aftermarket calibrations.
PIP5711A2020-11-16. Service bulletin. ENGINE; ELECTRICAL SYSTEM. This Preliminary information communicates to the dealer technicians a warm engine knock noise has no short or long term effects on the engine. Do not attempt repairs for this noise.
PIP5752F2020-11-16. Service bulletin. ENGINE AND ENGINE COOLING. This Preliminary information communicates A Vehicle may have a concern of service engine light, misfire and engine noise with possible of DTC P0300 P0106 P0506, Possible valve spring concern
PIP5750A2020-11-16. Service bulletin. ENGINE AND ENGINE COOLING. This Preliminary information communicates the possibility of the having dtc p06DD P06DA P06DB due to engine wiring harness concerns.
PIT5387H2020-11-16. Service bulletin. EQUIPMENT; ELECTRICAL SYSTEM. This Preliminary Information communication provides information to the technician how to repair vehicles that Instrument Panel Cluster, Radio, and Heater-Vent-Air Conditioning display blanks out, Bluetooth phone or Pandora connection dropped, the radio station or volume changes when operating the snow plow. Please advise the customer that engineering is aware of this concern and working on this issue.
PIT5734A2020-11-16. Service bulletin. EQUIPMENT:APPLIANCE:AIR CONDITIONER. This Preliminary information communicates an issue with poor heater performance and advises dealerships to inspect the heater core inlet and outlet hoses for being twisted or kinked.
PIT5736A2020-11-16. Service bulletin. EQUIPMENT:APPLIANCE:AIR CONDITIONER. This Preliminary information communicates how the HVAC setting operates during a remote vehicle start.

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