Diagnostic Aids

WARNING: This page is about a different car, the 2019 Buick Cascada, 2018 Buick Cascada, and 2017 Buick Cascada. However, it is still accessible from the selected car via links, so may be relevant.

The post catalyst fuel trim diagnostic is very sensitive to heated oxygen sensor (HO2S) design. A non-OE sensor or an incorrect part number may cause a DTC to set.
Certain aftermarket air filters may cause a DTC to set.
Certain aftermarket air induction systems or modifications to the air induction system may cause a DTC to set.
Certain aftermarket exhaust system components may cause a DTC to set.