The engine control module, or ECM, controls plenty of functions during routine driving, so any issues with that part could cause severe problems.

The Engine Control Module (ECM) is the computer responsible for controlling the engine. The ECM communicates with other vehicle control units via a communication bus.

GM has published a service bulletin describing a fix for 2021 Cadillac CT4 sedans with an Engine Control Module that fails to report catalytic converter faults.

The power control module, aka PCM, manages the engine, transmission and other systems based on information it receives from various sensors around the vehicle.

A fix is now available for 2021 Cadillac CT5 sedans affected by an Engine Control Module (ECM) issue leading to non-reporting of catalytic converter faults.

Although “ECU” typically stands for engine control unit, it could also mean electronic control unit. Here’s what those mean.