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Service bulletins for the 2021 Cadillac CT4

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.

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

By type

By component

By trouble code

By topic

Only bulletins with component: Heating and air conditioning are shown. Show all

Bulletins, newest first
PIT5099G2023-12-26. Service bulletin. VISIBILITY:DEFROSTER/DEFOGGER/HVAC SYSTEM. This Preliminary Information communication provides information to the technician about vehicles that the Heater-Vent-Air Conditioning blows warm air. Before calling General Motors Technical Assistance Center technician will need to have high and low pressures, outside temperature, humidity, and vent temperature.
PIP5540J2023-01-30. Service bulletin. VISIBILITY:DEFROSTER/DEFOGGER/HVAC SYSTEM:REAR WINDOW:ELECTRICAL HEATING ELEMENT. This Preliminary information communicates to the technician the need to inspect the induction system for potential icing issues in very cold ambient temperatures. To allow the ice to melt so that it can be drained from the related components. That any of the listed DTC's may set with or without poor engine performance.
PIT5099F2022-07-25. Service bulletin. VISIBILITY:DEFROSTER/DEFOGGER/HVAC SYSTEM. This Preliminary Information communication provides information to the technician about vehicles that the Heater-Vent-Air Conditioning blows warm air. Before calling General Motors Technical Assistance Center technician will need to have high and low pressures, outside temperature, humidity, and vent temperature.
12-01-37-001F2022-07-12. Service bulletin. EQUIPMENT; ENGINE AND ENGINE COOLING; VISIBILITY:DEFROSTER/DEFOGGER/HVAC SYSTEM. This service bulletin provides information to dealership personnel on a new refrigerant (R1234yf) for A/C service.
21NA2562021-12-27. Service bulletin. EXTERIOR LIGHTING; EQUIPMENT; VISIBILITY:DEFROSTER/DEFOGGER/HVAC SYSTEM:ENGINE COOLANT HOSES AND FITTINGS. This service bulletin provides repair information for dealers/technicians to correct a customer concern of a Malfunction Indicator Lamp Illuminated with DTC P26BB Set.

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