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Service bulletins for the 2020 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.

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

By type

By component

By trouble code

By topic

Bulletins, newest first
18-NA-0992024-02-02. Service bulletin. EQUIPMENT:OTHER:OWNERS/SERVICE/OTHER MANUAL. This bulletin provides information for use on a Product Assistance Claim (PAC), which is formerly known as a Product Allegation Resolution (PAR) claim.
PI1394B2024-02-02. Service bulletin. POWER TRAIN; ENGINE AND ENGINE COOLING. This PI bulletin advises the technician on the proper way to install the pistons in an engine.
PI0592I2024-02-02. Service bulletin. ELECTRICAL SYSTEM. This preliminary information (PI) provides information om Service Programming System (SPS) Error Codes (E4398, E4399, E4403, M4404, M4413, M6954, M6955, E4414, E4423, E4491 or E6961).
PIT5074P2024-01-29. Service bulletin. EQUIPMENT. This Preliminary Information communication provides information to the technician about the use of J-35616-64B terminal test probe, replacement terminals, and terminated leads. The J-35616-64B is the latest test probe released for checking tension or probing the .64 series terminals. The test probe terminal has been released in the terminal repair kit (J-38125-620H) located in Lear Tray 7 part number 963716-2. There are 5 terminated leads in a package part number is 13505346, which can be ordered through your normal General Motors Customer Care and Aftersales parts channel.
PIT5962A2024-01-29. Service bulletin. ELECTRICAL SYSTEM:HAND HEATER:WIRING HARNESS; UNKNOWN OR OTHER. This Preliminary information communicates a GM part number for reflective high temperature heat or insulating tape when repairing wiring harnesses.
PIT5851D2024-01-29. Service bulletin. ELECTRICAL SYSTEM:INSTRUMENT PANEL:SPEEDOMETER/ODOMETER. This Preliminary information communicates an issues with the odometer being incorrect after a programming event and how the dealership can resolve the issue.
02-08-42-001J2024-01-19. Service bulletin. EXTERIOR LIGHTING. This informational bulletin provides information for dealers/technicians on Headlamp, Tail Lamp, License Lamp or Fog/Driving Lamp Damage.
16-NA-3612024-01-13. Service bulletin. POWER TRAIN; EQUIPMENT. This service bulletin provides service /diagnostic information to aid with a Transmission Harsh 1-2 Shift Upon First Start Up/Shift of the Day Under Light Throttle.
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.
PIT5698D2023-12-26. Service bulletin. ELECTRICAL SYSTEM. This Preliminary information communicates additional information on how a LIN bus operates and diagnostic tips when working on a LIN bus.
23-NA-2192023-12-21. Service bulletin. EQUIPMENT:OTHER:OWNERS/SERVICE/OTHER MANUAL; EQUIPMENT. This service bulletin provides information on Concerns or Questions Regarding Installation of Dealer Installed Accessories.
PIP5700E2023-12-18. Service bulletin. ELECTRICAL SYSTEM. This Preliminary information communicates to the dealer technician that the part numbers for the internal wiring harnesses for the 8 speed RWD transmissions are not listed in the Electronic Parts Catalog. Technicians are to refer to the information provided in this document to obtain the internal wiring harness part numbers by application.
PIT5985C2023-12-18. Service bulletin. POWER TRAIN. This Preliminary information communicates diagnostic tips on how to resolve a issues with vehicles that will not power up after a can bus 2 issue, lightning strike, or a failed over the air update.
PIT5832K2023-12-18. Service bulletin. POWER TRAIN. This Preliminary information communicates a diagnostic tip on how to resolve a issue if the serial data authentication configuration did not complete correctly.
PIT5214F2023-12-18. Service bulletin. SUSPENSION. This Preliminary Information communication provides information to the technician about vehicles that have had multiple repair attempts that are being performed on customer?s vehicles that exhibit vibration conditions without utilizing the support of General Motors Technical Assistance Center. If valid vibration frequency or Road Force Variation data has been collected and a repair attempt does not correct the customer complaint, contact General Motors Technical Assistance Center for further support. For any vehicles that remains unrepaired after being at the dealer for three days or more and a related bulletin or PI is not found, contact General Motors Technical Assistance Center for further support.
23-NA-2142023-12-15. Service bulletin. ENGINE AND ENGINE COOLING. This informational bulletin provides Information on Purge Pump Part Replacement and Purge Part Number Interchange.
20-NA-1322023-12-15. Service bulletin. ENGINE AND ENGINE COOLING; EQUIPMENT; ELECTRICAL SYSTEM. This warranty administration bulletin provides policy information on the requirements for 12V battery testing and warranty replacements.
20-NA-0182023-12-09. Service bulletin. EQUIPMENT; ELECTRICAL SYSTEM. This service bulletin provides information for dealers/technicians on MDI 2 Required When Programming Vehicles with Vehicle Intelligence Platform (VIP).
23-NA-2062023-12-06. Service bulletin. ELECTRICAL SYSTEM; EQUIPMENT. This service bulletin provides information for dealers/technicians on History DTCs To Ignore / NO SES / NO Malfunction Indicator Lamps / NO Warning Messages.
PIP59432023-12-04. Service bulletin. EQUIPMENT:MECHANICAL:POWER TAKE-OFF (PTO); POWER TRAIN. This Preliminary Information communication advises the technician on diagnostic aids to help with the diagnosis and repair of 8 Speed Transmissions
21-NA-1352023-11-29. Service bulletin. ENGINE AND ENGINE COOLING; EQUIPMENT; EXTERIOR LIGHTING; ELECTRICAL SYSTEM. This service bulletin provides information to inform dealership personnel about Law Enforcement and Government vehicles that request to disable or enable content.
17-NA-0872023-11-29. Service bulletin. WHEELS; STEERING; SUSPENSION. This service bulletin provides information on Characteristics of Wide Low Aspect Ratio Tires, Vehicle Pulls Left or Right, Wanders, Follows Depressions in Road Surface, Tramlining.
03-00-91-001I2023-11-22. Service bulletin. WHEELS; POWER TRAIN; STEERING; SUSPENSION; ENGINE AND ENGINE COOLING. This service bulletin provides a vibration analysis worksheet the technician can use in conjunction with the appropriate Vibration Analysis-Road testing procedure when diagnosing vibration concerns.
20-NA-1592023-11-15. Service bulletin. WHEELS. This Warranty Administration bulletin is for information on General Motors New Vehicle Tire Warranty Program (U.S. Dealers Only).
23-NA-1892023-11-15. Service bulletin. ELECTRICAL SYSTEM; EQUIPMENT. This service bulletin assists technicians in setting up PicoScope hardware/software to monitor CAN bus traffic (voltage patterns) to aid Technical Assistance (TAC) and Field Service Engineers (FSEs) in diagnosing electrical issues present on network communication circuits.

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