Cadillac CT4 2021 — technical service bulletin

Official summary

Service Update - Certain vehicles with a 2.0L engine have an Engine Control Module (ECM) that may not properly diagnose, may not set Diagnostic Trouble Codes (DTCs), or may not illuminate the Malfunction Indicator Light (Check Engine Light) if certain fault conditions of the catalytic converter were to occur. 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 r

Vehicles covered

• 2021 Cadillac CT4
• 2021 Cadillac CT5