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Service bulletins for the 2021 Chevrolet 4500HD

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.

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

By type

By component

By trouble code

By topic

Only bulletins with component: Transmission and driveline are shown. Show all

Bulletins, newest first
06-00-89-031H2022-10-11. Service bulletin. POWER TRAIN; ENGINE AND ENGINE COOLING. This service bulletin provides information on OEM and Remanufactured Engine and Automatic Transmission/Transaxle Identification.
22-NA-1812022-09-19. Service bulletin. POWER TRAIN. This diagnostic tip advises the tech not to separate the flexplate from the torque convertor or damage my occur if the engine is started while diagnosing for noise from the engine or transmission.
17NA0502022-05-31. Service bulletin. POWER TRAIN:MANUAL TRANSMISSION:INTERNAL:SHAFT:INTERMEDIATE/LAY; ENGINE AND ENGINE COOLING:ENGINE:ENGINE CONTROL MODULE (ECU/ECM); FUEL SYSTEM, DIESEL. This informational bulletin explains how a health report is required when doing repairs on LCF vehicles.
18-NA-3392022-05-06. Service bulletin. POWER TRAIN. This informational bulletin provides information for dealers/technicians on approved 6-speed aisin automatic transmission on vehicle internal repairs.
990420002L2021-08-09. Service bulletin. POWER TRAIN:MANUAL TRANSMISSION; POWER TRAIN:AUTOMATIC TRANSMISSION; EQUIPMENT. This service bulletin provides information on Driveline Clunk Noise and what is acceptable and what is considered normal operation.
080730035E2021-08-09. Service bulletin. EQUIPMENT; EQUIPMENT ADAPTIVE/MOBILITY; POWER TRAIN. This bulletin provides information on the harmful effects of water or ethylene glycol in transmission fluid.

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