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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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By component

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Only bulletins with type: Service campaign are shown. Show all

Bulletins, newest first
N2525155902026-01-27. Service campaign. ELECTRICAL SYSTEM. Certain vehicles listed above, may have a condition in which the body-to-chassis ground strap may be corroded. Dealers will replace the ground strap.
N252494003-022026-01-21. Service campaign. ENGINE. Certain vehicles listed above, may have a condition where the connecting rod and/or crankshaft engine components in these vehicles may have manufacturing defects that can lead to engine damage and engine failure. This special coverage covers if an engine failure occurs in the vehicle as a result of the condition described above for a period of 10 years or 150,000 miles (240,000 km), whichever occurs first, from the date the vehicle was originally placed in service, regardless of ownership. For vehicles covered by Vehicle Service Contracts, all eligible claims with repair orders on or after May 23, 2025, are covered by this special coverage and must be submitted using the labor operation codes provided with this bulletin. Claims with repair orders prior to May 23, 2025, must be submitted to the Service Contract provider. Vehicle owners or lessees who paid for repairs referenced in this Special Coverage (“Customers”) are eligible for reimbursement of their reasonable and customary expenses in accordance with the procedures specified below. The conditional right to reimbursement is provided by GM solely in the interest of customer satisfaction and is personal to Customers. Customers may not assign and GM does not consent to any assignment of any Customer’s right to submit reimbursement claims, or to receive reimbursement, or any other rights granted by this Special Coverage to any third party, including but not limited to service contract providers, and this Special Coverage is not intended to and does not confer any third party beneficiary, subrogation or contribution rights, or any other rights to reimbursement, against GM, whether in law, equity or otherwise, on any third parties. Dealers are to replace the engine. The repairs will be made at no charge to the customer.
N2525342002026-01-06. Service campaign. UNKNOWN OR OTHER. General Motors has decided to conduct a voluntary emissions recall. A Vehicle Emissions Control Information (VECI) label with correct information may not be present. Dealers are to install a new VECI label.
N242454441 -032025-10-09. Service campaign. POWER TRAIN. Certain vehicles listed above, may have a condition where the transmission control valve has worn, resulting in a gradual loss of pressure within the valve. The effects can cause harsh shifting, setting a service engine soon message, reduced engine performance or P0747 diagnostic trouble code. Dealers are to install a new control valve body. The repairs will be made at no charge to the customer.
N2525083412025-09-16. Service campaign. ENGINE. Certain vehicles listed above, may have a condition that could cause the engine coolant control valve to fail an onboard vehicle diagnostic test. If this condition were to occur, the Malfunction Indicator Lamp (Check Engine Light) will illuminate, and a diagnostic trouble code will set. Additionally in some cases, the engine cooling fans may run after the engine is switched off. Dealers are to replace the engine coolant control valve as necessary. The repairs will be made at no charge to the customer.
N252510321-022025-09-05. Service campaign. UNKNOWN OR OTHER. Certain vehicles will receive a software update to add to the existing Check Engine Light a Driver Information Center (DIC) warning message if DTC P0016 sets. Dealers will reprogram the Engine Control Module (ECM). Owners who have accepted applicable terms and conditions will have the opportunity to accept these software changes using wireless over-the-air (OTA) technology without having to bring their vehicle to a dealership. Alternatively, owners may have their vehicle serviced at a GM dealer to receive these software updates.
N252510321-012025-08-28. Service campaign. UNKNOWN OR OTHER. Certain vehicles will receive a software update to add to the existing Check Engine Light a Driver Information Center (DIC) warning message if DTC P0016 sets. Dealers will reprogram the Engine Control Module (ECM). Owners who have accepted applicable terms and conditions will have the opportunity to accept these software changes using wireless over-the-air (OTA) technology without having to bring their vehicle to a dealership. Alternatively, owners may have their vehicle serviced at a GM dealer to receive these software updates.
N2525103212025-08-14. Service campaign. UNKNOWN OR OTHER. Certain vehicles will receive a software update to add to the existing Check Engine Light a Driver Information Center (DIC) warning message if DTC P0016 sets. Dealers will reprogram the Engine Control Module (ECM). Owners who have accepted applicable terms and conditions will have the opportunity to accept these software changes using wireless over-the-air (OTA) technology without having to bring their vehicle to a dealership. Alternatively, owners may have their vehicle serviced at a GM dealer to receive these software updates.
N252494003-012025-06-26. Service campaign. POWER TRAIN. Certain vehicles listed above, may have a condition where the connecting rod and/or crankshaft engine components in these vehicles may have manufacturing defects that can lead to engine damage and engine failure. This special coverage covers if an engine failure occurs in the vehicle as a result of the condition described above for a period of 10 years or 150,000 miles (240,000 km), whichever occurs first, from the date the vehicle was originally placed in service, regardless of ownership. For vehicles covered by Vehicle Service Contracts, all eligible claims with repair orders on or after May 23, 2025, are covered by this special coverage and must be submitted using the labor operation codes provided with this bulletin. Claims with repair orders prior to May 23, 2025, must be submitted to the Service Contract provider. Vehicle owners or lessees who paid for repairs referenced in this Special Coverage (“Customers”) are eligible for reimbursement of their reasonable and customary expenses in accordance with the procedures specified below. The conditional right to reimbursement is provided by GM solely in the interest of customer satisfaction and is personal to Customers. Customers may not assign and GM does not consent to any assignment of any Customer’s right to submit reimbursement claims, or to receive reimbursement, or any other rights granted by this Special Coverage to any third party, including but not limited to service contract providers, and this Special Coverage is not intended to and does not confer any third party beneficiary, subrogation or contribution rights, or any other rights to reimbursement, against GM, whether in law, equity or otherwise, on any third parties. Dealers are to replace the engine. The repairs will be made at no charge to the customer.
N252494770-012025-06-20. Service campaign. UNKNOWN OR OTHER. Amendments to the Song-Beverly Act (SBA) California warranty law provides vehicle owners with an opportunity to submit a written notice to GM before filing a lawsuit seeking a vehicle repurchase. If such a notice is not provided to GM, then the vehicle owner is prevented from seeking civil penalties in litigation. Vehicle owners of the affected vehicles will be mailed an owner’s manual and warranty insert containing this information in English and Spanish.
N2524947702025-06-17. Service campaign. UNKNOWN OR OTHER. Amendments to the Song-Beverly Act (SBA) California warranty law provides vehicle owners with an opportunity to submit a written notice to GM before filing a lawsuit seeking a vehicle repurchase. If such a notice is not provided to GM, then the vehicle owner is prevented from seeking civil penalties in litigation. Vehicle owners of the applicable vehicles will be mailed an owner’s manual and warranty insert containing this information in English and Spanish.
N2524940032025-05-23. Service campaign. ENGINE. Certain vehicles listed above, may have a condition where the connecting rod and/or crankshaft engine components in these vehicles may have manufacturing defects that can lead to engine damage and engine failure. This special coverage covers if an engine failure occurs in the vehicle as a result of the condition described above for a period of 10 years or 150,000 miles (240,000 km), whichever occurs first, from the date the vehicle was originally placed in service, regardless of ownership. For vehicles covered by Vehicle Service Contracts, all eligible claims with repair orders on or after May 23, 2025, are covered by this special coverage and must be submitted using the labor operation codes provided with this bulletin. Claims with repair orders prior to May 23, 2025, must be submitted to the Service Contract provider. Vehicle owners or lessees who paid for repairs referenced in this Special Coverage (“Customers”) are eligible for reimbursement of their reasonable and customary expenses in accordance with the procedures specified below. The conditional right to reimbursement is provided by GM solely in the interest of customer satisfaction and is personal to Customers. Customers may not assign and GM does not consent to any assignment of any Customer’s right to submit reimbursement claims, or to receive reimbursement, or any other rights granted by this Special Coverage to any third party, including but not limited to service contract providers, and this Special Coverage is not intended to and does not confer any third party beneficiary, subrogation or contribution rights, or any other rights to reimbursement, against GM, whether in law, equity or otherwise, on any third parties. Dealers are to replace the engine. The repairs will be made at no charge to the customer.
N242454441-022025-01-28. Service campaign. POWER TRAIN. Certain vehicles listed above, may have a condition where the transmission control valve has worn, resulting in a gradual loss of pressure within the valve. The effects can cause harsh shifting, setting a service engine soon message, reduced engine performance or P0747 diagnostic trouble code. This special coverage covers the condition described above for a period of 15 years or 150,000 miles (240,000km), whichever occurs first, from the date the vehicle was originally placed in service, regardless of ownership. For vehicles covered by Vehicle Service Contracts, all eligible claims with repair orders on or after November 26, 2024, are covered by this special coverage and must be submitted using the labor operation codes provided with this bulletin. Claims with repair orders prior to November 26, 2024, must be submitted to the Service Contract provider. Vehicle owners or lessees who paid for repairs referenced in this Special Coverage (“Customers”) are eligible for reimbursement of their reasonable and customary expenses in accordance with the procedures specified below. The conditional right to reimbursement is provided by GM solely in the interest of customer satisfaction and is personal to Customers. Customers may not assign and GM does not consent to any assignment of any Customer’s right to submit reimbursement claims, or to receive reimbursement, or any other rights granted by this Special Coverage to any third party, including but not limited to service contract providers, and this Special Coverage is not intended to and does not confer any third party beneficiary, subrogation or contribution rights, or any other rights to reimbursement, against GM, whether in law, equity or otherwise, on any third parties. Dealers are to install a new control valve body. The repairs will be made at no charge to the customer.
N242454441-012024-12-12. Service campaign. POWER TRAIN. Certain vehicles listed above, may have a condition where the transmission control valve has worn, resulting in a gradual loss of pressure within the valve. The effects can cause harsh shifting, setting a service engine soon message, reduced engine performance or P0747 diagnostic trouble code. This special coverage covers the condition described above for a period of 15 years or 150,000 miles (240,000km), whichever occurs first, from the date the vehicle was originally placed in service, regardless of ownership. For vehicles covered by Vehicle Service Contracts, all eligible claims with repair orders on or after November 26, 2024, are covered by this special coverage and must be submitted using the labor operation codes provided with this bulletin. Claims with repair orders prior to November 26, 2024, must be submitted to the Service Contract provider. Vehicle owners or lessees who paid for repairs referenced in this Special Coverage (“Customers”) are eligible for reimbursement of their reasonable and customary expenses in accordance with the procedures specified below. The conditional right to reimbursement is provided by GM solely in the interest of customer satisfaction and is personal to Customers. Customers may not assign and GM does not consent to any assignment of any Customer’s right to submit reimbursement claims, or to receive reimbursement, or any other rights granted by this Special Coverage to any third party, including but not limited to service contract providers, and this Special Coverage is not intended to and does not confer any third party beneficiary, subrogation or contribution rights, or any other rights to reimbursement, against GM, whether in law, equity or otherwise, on any third parties. Dealers are to install a new control valve body. The repairs will be made at no charge to the customer.
N2424506312024-09-18. Service campaign. ENGINE. Service Update. Certain vehicles equipped with a 2.7L engine (RPO L3B), may have an Engine Control Module (ECM) that does not sufficiently control fuel injector flow rate under certain driving conditions. Dealers are to reprogram the ECM.
N2223897222024-08-28. Service campaign. ELECTRICAL SYSTEM. Certain vehicles may have a condition in which a transmission control body screen detaches from the spacer plate when the vehicle is operated in extremely cold weather conditions. Dealers are to reprogram the Transmission Control Module.
General Communication2024-08-26. Service campaign. ELECTRICAL SYSTEM. Vehicle Wide Programming (VWP) is a new process to update software on GM Vehicles. It provides the ability via a single selection within Techline Connect to first identify which modules need updating and then proceed to updating affected modules (with some exceptions). The updating of modules is completed in parallel instead of the technician needing to update one module at a time. This allows a more streamlined approach for dealers and customers.

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