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Service bulletins for the 2020 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.

1990 on file from NHTSA, as of 2026-10-19.

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Bulletins, newest first
20NA1002020-08-10. Service bulletin. ENGINE; ELECTRICAL SYSTEM. This informational bulletin provides information for dealers/technicians on Engine Control Module Calibration for T1 L3B Engine with DTC P26BB Set.
20NA0592020-08-10. Service bulletin. STRUCTURE:BODY:TAILGATE:HINGE AND ATTACHMENTS. This technical bulletin provides repair information to correct a customer concern of the pickup box endgate will not fully close by itself.
20NA0122020-08-10. Service bulletin. EQUIPMENT:ELECTRICAL:RADIO/TAPE DECK/CD ETC.; ELECTRICAL SYSTEM:SOFTWARE. This Technical bulletin provides service procedure information for dealers/technicians on Radio Software Version V135116 Over-the-Air Update.
19NA2282020-08-10. Service bulletin. POWER TRAIN:AUTOMATIC TRANSMISSION:CONTROL MODULE (TCM/PCM/TECM); ELECTRICAL SYSTEM. This technical provides a procedure to locate, disconnect and re-connect the TCM electrical connector if found the cause of the customers concerns.
16NA3802020-08-10. Service bulletin. ENGINE AND ENGINE COOLING:EXHAUST SYSTEM:MANIFOLD/HEADER/MUFFLER/TAIL PIPE. 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.
N202294740 012020-07-20. Service bulletin. ELECTRICAL SYSTEM:SOFTWARE; STEERING. Service Update - Certain vehicles may require individual software updates to multiple modules to address various minor issues such as steering feel and data communication. Dealers are to reprogram multiple modules.
N202306491 Messa2020-07-20. Service bulletin. STRUCTURE:BODY:HOOD; EQUIPMENT ADAPTIVE/MOBILITY. Service Update (Revised Population). The purpose of this service update is to provide the customer with a goodwill gift to offset customer inconvenience, restore confidence in GM, and maintain loyalty to GM. The vehicles involved in this service update have previously had a hood assembly replacement under recall N192284960. These customers are now being asked to bring their vehicle back in for another hood replacement under Safety Recall N202306490. For their inconvenience, dealers are to offer the customer a selection of one of the available goodwill tools listed in this bulletin. Because each customer has unique preferences, please offer all options found in this bulletin to the customer and allow them to select the one that best suits their situation. Please note that not all vehicles in Safety Recall N202306490 are included in this service update. The goodwill offer described in this bulletin should be presented to the involved customer when they pick up their vehicle after having Safety Recall N202306490 performed on the vehicle. Population reduced.
N2023064912020-07-20. Service bulletin. STRUCTURE:BODY:HOOD; EQUIPMENT ADAPTIVE/MOBILITY. Service Update. The purpose of this service update is to provide the customer with a goodwill gift to offset customer inconvenience, restore confidence in GM, and maintain loyalty to GM. The vehicles involved in this service update have previously had a hood assembly replacement under recall N192284960. These customers are now being asked to bring their vehicle back in for another hood replacement under Safety Recall N202306490. For their inconvenience, dealers are to offer the customer a selection of one of the available goodwill tools listed in this bulletin. Because each customer has unique preferences, please offer all options found in this bulletin to the customer and allow them to select the one that best suits their situation. Please note that not all vehicles in Safety Recall N202306490 are included in this service update. The goodwill offer described in this bulletin should be presented to the involved customer when they pick up their vehicle after having Safety Recall N202306490 performed on the vehicle.
N1922878402020-06-29. Service bulletin. ELECTRICAL SYSTEM:WIRING; ENGINE. Service Update - Certain vehicles equipped with a 2.7L turbo engine (RPO L3B), may have a condition where the engine wiring harness may have been wrapped and/or routed incorrectly, creating the potential for wear-through in several locations. If this occurred it could allow the engine harness to short to ground and/or be severed, which may lead to a check engine light, reduced engine power, no start condition or in rare cases a stall. Dealers are to inspect harness for correct tape wrapping and install engine harness sleeves.
N2023007912020-06-29. Service bulletin. ENGINE AND ENGINE COOLING:EXHAUST SYSTEM; FUEL SYSTEM, DIESEL; ENGINE AND ENGINE COOLING:ENGINE:DIESEL. Service Update - In some vehicles, equipped with diesel engines, the Diesel Exhaust Fluid (DEF) system may not immediately reactivate, as it should, after the vehicle?s control system finds that a DEF heater fault is no longer present. In these vehicles, after such a fault is detected as absent, DEF system reactivation, including DEF injection, may not occur until the ignition key is cycled. Dealers are to reprogram the reductant control module.
N1922724002020-06-29. Service bulletin. ELECTRICAL SYSTEM; POWER TRAIN:AUTOMATIC TRANSMISSION; WHEELS. Customer Satisfaction Program - Certain 2019-2020 model year Chevrolet Silverado and GMC Sierra vehicles, equipped with an 8-Speed Automatic Transmission, may have a condition where the rear wheels will lock up at low speeds. An intermittent short circuit is being caused by wire bonds moving under high current and thermal load, making contact with adjacent wire(s) in the transmission control module (TCM). Dealers will replace the TCM.
N2022995202020-06-29. Service bulletin. BACK OVER PREVENTION: BACK-UP ALARM. Customer Service Program - Certain vehicles may not have the backup alarm which should have been included the dealer kit. Dealers are to provide the missing backup alarm to the customer.
N1922828602020-06-29. Service bulletin. POWER TRAIN. Service Update - Certain vehicles may have a condition where the transmission enters a neutral state when the internal range sensor (IRS) fault is active. Dealers are to reprogram the transmission control module.
N2022983302020-06-29. Service bulletin. EQUIPMENT. Customer Satisfaction Program - Certain 2020 Chevrolet Silverado HD and GMC Sierra HD vehicles were intended to include a high idle feature, (RPO UF3). Equipment not included on the vehicle is required for the ?high idle? feature to function properly. Because the vehicle does not have the required equipment, this feature cannot be activated and will not be available for use. Dealers will issue the customer a reimbursement check.
N2022949602020-06-29. Service bulletin. SUSPENSION; WHEELS. Customer Satisfaction Program - Vehicles may have been built with 3500 series single rear wheel leaf springs. In service, if a single leaf spring were to be replaced, a 2500 series spring could be installed which would cause the vehicle to have mismatching springs. Dealers are to replace with the correct rear leaf springs.
PIE0568B2020-06-22. Service bulletin. ELECTRICAL SYSTEM. This engineering information (EI) is requesting information from technicians to perform the check list provided and contact the engineer listed in regards to Shift to Park Message on Drivers Information Center (DIC) (ONLY On Push Button Ignition), Unable to Remove Key from Ignition Cylinder and/or Difficult to Shift Out of Park.
PIE0568A2020-06-22. Service bulletin. ELECTRICAL SYSTEM. This engineering information (EI) is requesting information from technicians to perform the check list provided and contact the engineer listed in regards to Shift to Park Message on Drivers Information Center (DIC) (ONLY On Push Button Ignition), Unable to Remove Key from Ignition Cylinder and/or Difficult to Shift Out of Park.
PIE05682020-06-22. Service bulletin. ELECTRICAL SYSTEM. This engineering information (EI) is requesting information from technicians to perform the checklist provided and contact the engineer listed in regards to Shift to Park Message on Drivers Information Center (DIC) (ONLY On Push Button Ignition), Unable to Remove Key from Ignition Cylinder and/or Difficult to Shift Out of Park.
PIE05672020-06-22. Service bulletin. ELECTRICAL SYSTEM; EQUIPMENT. This engineering information (EI) is requesting information from technicians to perform the check list provided and contact the engineer listed in regards to SD Code messages displayed on the Radio Screen and/or Instrument Cluster - Navigation System Malfunction.
PIE05662020-06-22. Service bulletin. ELECTRICAL SYSTEM. This engineering information (EI) is requesting information from technicians to perform the check list provided and contact the engineer listed in regards to the Malfunction Indicator Lamp (MIL) Illuminated and/or functional failures of the Airflow Shutter.
PIE0563A2020-06-22. Service bulletin. ENGINE. This engineering information (EI) is requesting information from technicians to perform the check list provided and contact the engineer listed in regards to oil leaking from the oil pan.
140604004G2020-06-22. Service bulletin. ENGINE. This informational bulletin explains the normal noises an engine may make when the ambient temperature outside is cold or the vehicle has sat for a few hours.
070849020Q2020-06-22. Service bulletin. ELECTRICAL SYSTEM. This informational bulletin provides information for the IPC odometer programming method quick reference guide.
060089029T2020-06-22. Service bulletin. ELECTRICAL SYSTEM: INSTRUMENT CLUSTER/PANEL; EQUIPMENT. This informational bulletin includes information on Interior Cleaning - Instrument Panel (IP), Hard or Plastic Surfaces, Seats, Carpet, Leather, Vinyl, Fabric Cleaner, Stain Remover, Restorer - Product Availability.
060089029S2020-06-22. Service bulletin. ELECTRICAL SYSTEM: INSTRUMENT CLUSTER/PANEL; EQUIPMENT. This informational bulletin includes information on Interior Cleaning - Instrument Panel (IP), Hard or Plastic Surfaces, Seats, Carpet, Leather, Vinyl, Fabric Cleaner, Stain Remover, Restorer - Product Availability.

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