The General has issued a service bulletin describing a fix for certain units of the 2021 Cadillac CT4 compact luxury sedan that may be affected by an incorrectly calibrated Engine Control Module (ECM) potentially unable to detect and/or indicate catalytic converter faults.
The ECM software may be correctly recalibrated without dealer service by wireless over-the-air updates in some cases, but possibly affected 2021 Cadillac CT4 sedans should still be investigated to ensure the problem has been eliminated.
In 2021 Cadillac CT4 units with the incorrectly calibrated Engine Control Module, several problems may arise if there is a fault or failure in the car’s catalytic converter. The ECM may fail to indicate the fault by not illuminating the Check Engine light, can incorrectly diagnose the catalytic converter problem, or can fail to set Diagnostic Trouble Codes (DTCs) so that diagnostic processes won’t detect the fault.
This problem only affects Cadillac CT4 vehicles motivated by the turbocharged 2.0L LSY I4 gasoline engine, and does not apply to the sedan’s other available powerplant for the 2021 model year, the turbocharged 2.7L L3B I4 gasoline engine.
Dealers are instructed to inspect and, if necessary, apply the available remedy to all 2021 Cadillac CT4 units that may be in their inventory, as well as those vehicles brought in for service or other reasons by their owners. The first step is to check the Investigate Vehicle History screen in the GM Global Warranty Management system to see if the CT4 is marked “Open,” indicating the potential fault has not been corrected by OTA updates.
Once the dealer has verified a 2021 CT4 requires the fix, the remedy should be applied. No parts are needed to complete the repair, which involves reprogramming the Engine Control Module with the latest, up-to-date calibration. The whole process requires about half an hour.
2021 Cadillac CT4 owners who want more information about the service bulletin and fix, or have questions about the process, can contact Cadillac customer service at the telephone listed below, referring to the service bulletin number as needed:
Contacts:
- GM Customer service bulletin number: N232412712
- Cadillac Customer Service: 1-800-333-4223
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