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Service bulletin N202321920

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.

The communication, as NHTSA indexes it (as of 2026-10-19)
TypeService bulletin
NHTSA id10186054
Published by NHTSA2021-02-01
Manufacturer's numberN202321920
Manufacturer's date2020-12-21
NHTSA componentEQUIPMENT; ENGINE AND ENGINE COOLING

NHTSA's summary

Service Update. A small number of vehicles may have a coolant inlet pipe that may present an obstructed threaded hole for the coolant temp sensor which could result in the check engine light coming on or a potential coolant leak. Dealers are to replace the coolant inlet pipe and temperature sensor.

The document

The document is the manufacturer's. This site does not hold it. NHTSA files a document at one of these two addresses; we have not asked NHTSA which.

Components

Engine, Equipment and accessories

Vehicles listed
CADILLAC XT42021
CADILLAC XT52021
CHEVROLET TRAILBLAZER2021
GMC ACADIA2021

Listing a model year does not mean every vehicle of it is concerned: the document says which.

Recalls for the same vehicles and component
20213652021-06-10. Accessories
21V4400002021-06-10. EQUIPMENT:MECHANICAL:ACCESSORY SCISSOR/SCREW/BOTTLE JACK/LIFT:STAND
20V2950002020-05-21. EQUIPMENT:OTHER:LABELS; TIRES

A recall listed here may apply to some of the same vehicles. Only the manufacturer can say whether it applies to one vehicle.

Other bulletins for the same vehicles and component
00-06-01-026R2025-12-03. Service bulletin. This service bulletin provides information on replacing the intake manifold when the engine is replaced after severe internal engine damage.
23-NA-1532025-10-25. Service bulletin. The service bulletin advises the tech of a normal transmission shift condition and the delay in throttle response when the throttle plate is opened rapidly and advises the customer that it is normal for the delay.
N2525083502025-10-21. Service campaign. Certain vehicles listed above, may have a condition that could cause the engine coolant thermostat to open at a lower temperature than intended. 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. This special coverage covers the condition described above for a period of 15 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 October 21, 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 October 21, 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 coolant thermostat as necessary. The repairs will be made at no charge to the customer.
N242450640-012025-10-20. Warranty extension. Special Coverage. Certain 2021 model year Buick Encore GX and Chevrolet Trailblazer vehicles, equipped with a 1.2L engine, may have a condition that could cause the turbocharger to fail. If this condition occurs, the Malfunction Indicator Lamp (Check Engine Light) will illuminate, and a diagnostic trouble code will set. Additionally, a message may be displayed indicating the vehicle’s available engine power is reduced. This special coverage covers the condition described above for a period of 15 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 November 6, 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 6, 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 replace the turbocharger as necessary. The repairs will be made at no charge to the customer.
23-NA-1222025-10-01. Service bulletin. This service bulletin provides a procedure to fix an oil leak from a porous area at the cylinder head and how to fix it so that the engine does not have to be replaced.
15-NA-0102025-07-07. Service bulletin. This service bulletin provides information to dealership personnel for new vehicles with less than 1,000 miles that may not pass California smog inspection or smog inspection in other states.
24-NA-0682025-06-16. Service bulletin. This service bulletin provides a procedure to test and replace the battery distribution fuse block if found the cause of the DTC and electric coolant pump inoperative.
21-NA-2402025-06-16. Service bulletin. This service bulletin provides diagnostic repair information to correct an oil leak in the engine.
PIE0794E2025-06-12. Service bulletin. This engineering information (EI Lite) ends the need for gathering further information using the Field Product Reporting (FPR) App process for vehicles where customers comment on having oil leaking from the oil pan that drives a warrantable item type of repair on said vehicles.
25-NA-1002025-06-12. Service bulletin. This warranty administration bulletin provides policy information on vehicles outside of a California Emissions State who move to and register their vehicle in a California Emission State may be entitled to the 7 year, 70,000-mile Emission Select State Component Limited Warranty.