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
| PIT5744A | 2021-04-19. Service bulletin. VISIBILITY; BACK OVER PREVENTION. This Preliminary information communicates information on how to disable the Side Blind Zone Detection and Park Assist systems when a customer removes the pickup box from the vehicle to install an aftermarket bed or body. |
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| PIT5820 | 2021-04-19. Service bulletin. EQUIPMENT. This Preliminary information communicates an issues with an SES MIL and DTC P2B87 setting. Engineering has releasing updated cals to correct the concern. |
| PIT5544D | 2021-04-19. Service bulletin. STEERING; BACK OVER PREVENTION; POWER TRAIN. This Preliminary information communicates information on a hydrauilc rush type noise from the power steering gear. This noise is a characteristic of the new Active Hydraulic Assist System RPO NV8 and no repairs should be made. The noise is most noticeable in the cab at idle, in park, with all accessories turned off. |
| PIT5819 | 2021-04-19. Service bulletin. ENGINE AND ENGINE COOLING:EXHAUST SYSTEM:MANIFOLD/HEADER/MUFFLER/TAIL PIPE. This Preliminary information communicates in temperatures below freezing, it may be noticed that exhaust is only exiting from the right hand exhaust tailpipe. The cause of this condition is a low point in left side tailpipe which results in condensation building up at the low point in the tailpipe. In low temperatures the condensation can freeze and form ice limiting the flow of exhaust out of the left tailpipe. Dealers are to drill a small hole in the left tailpipe to allow condensation to drain. |
| PIP5655E | 2021-04-19. Service bulletin. STRUCTURE. This Preliminary information communicates to the dealer technician that the 10L1000 transmission and valve body assembly part restriction has ended. Dealers are advised that these transmissions and valve bodies can now be ordered through the regular GM CCA parts process or PQC process for required dealers (Canada). |
| PIP5776B | 2021-04-19. Service bulletin. STRUCTURE. This Preliminary information communicates that a vehicle may exhibit a misfire condition resulting in misfire codes P0300-P308. Upon diagnosis it may be discovered the lifter has come apart. It is recommended to replace the lifter guide and the four lifters. |
| PIP5784 | 2021-04-19. Service bulletin. STRUCTURE. This Preliminary information communicates to the dealer technician to inspect for a missing 1-2-7-8-R clutch fluid passage seal or incorrect 1-2-7-8-R clutch fluid passage seal being install for a no movement concern after valve body replacement on the 8L45 or 8L90 transmissions. |
| PIP5771B | 2021-04-19. Service bulletin. POWER TRAIN; STRUCTURE. This Preliminary information communicates to the dealer technician to replace the valve body on 8 speed transmissions setting DTC P0796 if no debris is found in the transmission fluid pan. If debris is found in the transmission fluid pan the technician is advised to repair the transmission as needed and replace the valve body. |
| PIP5783 | 2021-04-19. Service bulletin. EQUIPMENT:OTHER:OWNERS/SERVICE/OTHER MANUAL. This Preliminary information communicates to dealer technicians that DTC P026C are under investigation by GM Engineerinig. |
| PIE0610 | 2021-03-08. Service bulletin. EQUIPMENT; ELECTRICAL SYSTEM; EQUIPMENT ADAPTIVE/MOBILITY. This engineering information (EI) is requesting information from technicians to perform the check list provided and contact the engineer listed in regards to Loss of Power, Instrument Panel Cluster (IPC) Gauges are Inoperative and/or Fluctuate, Multiple Warning Lights on DIC. |
| PIE0609 | 2021-03-08. Service bulletin. EQUIPMENT ADAPTIVE/MOBILITY; ELECTRICAL SYSTEM; EQUIPMENT; ENGINE AND ENGINE COOLING. This engineering informational bulletin is requesting information from technicians to perform the check list provided and contact the engineer listed in regards to a noise heard from the engine compartment, loss of charging and/or reduced alternator output. |
| PIE0602 | 2021-03-08. Service bulletin. EQUIPMENT ADAPTIVE/MOBILITY; EQUIPMENT; ENGINE. This engineering information (EI) is requesting information from technicians to perform the check list provided and contact the engineer listed in regards to Service Engine Soon Lamp Illuminated On Driver Information Center (DIC), DTC P208B Set. |
| PIE0593A | 2021-03-08. Service bulletin. ELECTRICAL SYSTEM: INTEGRATED TRAILER BRAKE CONTROL; EQUIPMENT; SERVICE BRAKES. This engineering informational bulletin is requesting information from technicians to perform the check list provided and contact the engineer listed in regards the trailer brake being inoperative and/or check trailer brakes message on drivers information center (DIC). |
| PIE0590A | 2021-03-08. Service bulletin. ENGINE; EQUIPMENT; ELECTRICAL SYSTEM:INTERIOR LAMPS/BULBS. This engineering informational bulletin 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). |
| 150089004C | 2021-03-08. Service bulletin. SUSPENSION:FRONT:MACPHERSON STRUT; SUSPENSION:FRONT:SHOCK ABSORBER; POWER TRAIN:AUTOMATIC TRANSMISSION:FLUID/LUBRICANT. This service bulletin provides technicians with updated information to help identify the differences between what is considered a fluid leak, and what is considered fluid seepage. |
| 21NA026 | 2021-03-08. Service bulletin. EQUIPMENT; STRUCTURE; EQUIPMENT ADAPTIVE/MOBILITY. This service bulletin provides information for dealers/technicians on accessory all-weather floor liners and flat mats warped or misshapen. |
| 21NA012 | 2021-03-01. Service bulletin. EQUIPMENT; ELECTRICAL SYSTEM:SOFTWARE. This technical bulletin provides repair information to correct a customer concern of Clean Exhaust Filter, Perform Manual Regen, and Loss of Digital Speedometer DIC Displays. |
| 21NA007 | 2021-03-01. Service bulletin. ELECTRICAL SYSTEM; ENGINE AND ENGINE COOLING:EXHAUST SYSTEM:EMISSION CONTROL. This technical bulletin provides a procedure to program the reductant fluid module if found the cause of the customers concern. |
| 21NA006 | 2021-03-01. Service bulletin. ELECTRICAL SYSTEM; ENGINE AND ENGINE COOLING:EXHAUST SYSTEM:EMISSION CONTROL. This bulletin provides a possible location of a bad connection at the reductant fluid tanks electrical connector. |
| 21NA002 | 2021-03-01. Service bulletin. EQUIPMENT:ELECTRICAL:ENGINE BLOCK HEATER; ENGINE AND ENGINE COOLING:ENGINE:ENGINE CONTROL MODULE (ECU/ECM); FUEL SYSTEM, DIESEL. This informational bulletin provides a test procedure, for a possible faulty DEF Heater. |
| 20NA203 | 2021-03-01. Service bulletin. EQUIPMENT ADAPTIVE/MOBILITY; EQUIPMENT; ENGINE AND ENGINE COOLING:EXHAUST SYSTEM. This informational bulletin explains how the regen works for the DEF system and how it works at different levels. |
| 20NA110 | 2021-03-01. Service bulletin. FUEL SYSTEM, DIESEL; EQUIPMENT:OTHER:OWNERS/SERVICE/OTHER MANUAL; EQUIPMENT. 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. |
| 20NA105 | 2021-03-01. Service bulletin. ELECTRICAL SYSTEM:ADAS:HUD:CAMERA/SENSOR; EQUIPMENT ADAPTIVE/MOBILITY; EQUIPMENT; BACK OVER PREVENTION. This technical bulletin provides repair information to correct a customer concern of 360 Camera Views go Blank with Tailgate Removed. |
| 20NA020 | 2021-03-01. Service bulletin. SERVICE BRAKES. This technical bulleti provides a procedure to replace the front and rear brake pads if the brakes are squealing. |
| 18NA285 | 2021-03-01. Service bulletin. EQUIPMENT; FUEL SYSTEM, OTHER:KINETIC:CLUTCH. This informational bulletin advises the tech of a possible normal condition when the vehicle creeps forward during start up conditions when the clutch packs are full of residual oil. |
The summaries are NHTSA's. Each bulletin's page links NHTSA's copy of the manufacturer's document.