Engine Control Module (ECM) Commanded Reduced Engine Power

Under certain conditions the ECM may limit engine power by reducing engine torque and, for some vehicles, fuel pressure as well. For most, but not all of the conditions, the ECM will illuminate the reduced engine power lamp on the instrument panel cluster, however a DTC may not be set. Observe the scan tool Reduced Engine Power History parameter or refer to Engine Control Module Scan Tool Information (V8 Gasoline) to determine the reason for the reduced engine power event.

Verify or inspect for the following:

• Vehicle being driven inappropriately. Towing heavy loads up an incline for an extended period of time or operating the vehicle at sustained, excessively high engine speeds may cause the engine oil or coolant to overheat. A repair may not be necessary. Inspect the airflow passageways in front of the engine for obstructions and clear away any debris or foreign material that is found. If no obstructions or conditions are found, review approved driving habits with the customer. The customer may need to operate the vehicle at a higher engine speed to improve cooling system performance, or, at a slower engine speed to reduce engine load.
• Reduced engine power due to OnStar® remote command. A repair may not be necessary. Verify the vehicle is not in the OnStar® initiated Stolen Vehicle Slowdown mode. Refer to Remote Vehicle Speed Limiting Description and Operation , and Symptoms - Reduced Engine Power Message .