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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.

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Only bulletins with component: Fuel system are shown. Show all

Bulletins, newest first
N2023205102021-03-01. Service bulletin. AIR BAGS; ENGINE AND ENGINE COOLING; ELECTRICAL SYSTEM; FUEL SYSTEM, GASOLINE; EQUIPMENT. Customer Satisfaction Program. Certain vehicles, equipped with a gas engine, may have a condition in which the printed circuit board inside of the water pump may have been manufactured incorrectly potentially causing a water pump failure. The vehicle coolant system temperature is monitored and will display multiple warnings to the customer as coolant temperatures rise. At a set coolant temperature, the MIL will illuminate, DTC P2B85 will set in the engine control module (ECM), the oil pressure gauge will indicate high oil pressure and reduced torque with notification to the driver of reduced power will occur. If the customer continues to drive after this warning and the coolant temperature continues to rise, a chime will occur, the AC will be disabled and an additional message instructing the driver to idle will illuminate. If the customer continues to drive the vehicle after all previous warnings and the coolant temperature continues to rise a message the engine will shut down could occur, and the engine will be shut down. Dealers are to replace the water pump.
N2023205102021-02-16. Service bulletin. LANE DEPARTURE; FUEL SYSTEM, GASOLINE; SERVICE BRAKES, HYDRAULIC; ELECTRICAL SYSTEM; AIR BAGS; ENGINE AND ENGINE COOLING; POWER TRAIN. Customer Satisfaction Program. Certain vehicles, equipped with a gas engine, may have a condition in which the printed circuit board inside of the water pump may have been manufactured incorrectly potentially causing a water pump failure. The vehicle coolant system temperature is monitored and will display multiple warnings to the customer as coolant temperatures rise. At a set coolant temperature, the MIL will illuminate, DTC P2B85 will set in the engine control module (ECM), the oil pressure gauge will indicate high oil pressure and reduced torque with notification to the driver of reduced power will occur. If the customer continues to drive after this warning and the coolant temperature continues to rise, a chime will occur, the AC will be disabled and an additional message instructing the driver to idle will illuminate. If the customer continues to drive the vehicle after all previous warnings and the coolant temperature continues to rise a message the engine will shut down could occur, and the engine will be shut down. Dealers are to replace the water pump.
030604017O2020-12-21. Service bulletin. FUEL SYSTEM, DIESEL; ENGINE AND ENGINE COOLING:ENGINE:DIESEL. This Informational Bulletin provides information on availability of Diesel Fuel additives.
20NA1972020-12-21. Service bulletin. EQUIPMENT; FUEL SYSTEM, GASOLINE:FUEL INJECTION SYSTEM:FUEL RAIL. This technical bulletin provides a procedure to inspect and repair the fuel pressure sensor if found the cause of the customers concern.
PIT5161H2020-12-14. Service bulletin. EQUIPMENT ADAPTIVE/MOBILITY; FUEL SYSTEM, GASOLINE; EQUIPMENT. This Preliminary Information communication provides information to the technician about vehicles that may have a bump feel or clunk noise at a stop or on launch. Dealer should communicate to the customer this condition is a normal operating characteristic of their vehicle. The bump clunk issue may be due to fuel movement in the fuel tank when not completely full. The condition is eliminated after completely filling the fuel tank.
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.
19NA2372020-11-30. Service bulletin. FUEL SYSTEM, DIESEL; EQUIPMENT. This informational bulletin explains how to identify possible DEF contamination.
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.
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.
PIE0574A2020-10-26. Service bulletin. FUEL SYSTEM, OTHER; ENGINE. This engineering informational bulletin is requesting information from technicians to inspect for engine oil leak and contact the engineer listed.

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