* Throttle Position Sensor (TPS): A faulty TPS prevents the PCM from accurately reading the throttle's position, leading to inaccurate fuel and ignition timing. This is a very common cause of reduced engine power.
* Mass Airflow Sensor (MAF): A malfunctioning MAF sensor provides incorrect readings of the air entering the engine, resulting in a poor air/fuel mixture and triggering the reduced power mode.
* Crankshaft Position Sensor (CKP): This sensor tells the PCM where the crankshaft is in its rotation. A bad CKP sensor can cause erratic engine operation and the reduced power message.
* Cam Position Sensor (CMP): Similar to the CKP sensor, a faulty CMP sensor provides incorrect information about the camshaft's position.
* Throttle Body: A dirty or faulty throttle body can restrict airflow and cause this message.
* Low Fuel Pressure: Problems with the fuel pump, fuel filter, or fuel pressure regulator can lead to insufficient fuel delivery, resulting in reduced power.
* Ignition System Problems: Issues with spark plugs, ignition coils, or the ignition control module can also trigger the message.
* Oxygen Sensor (O2 Sensor): A faulty O2 sensor provides incorrect information about the exhaust gases, causing the PCM to adjust the air/fuel mixture inefficiently.
* Wiring Harness Issues: Damaged or corroded wiring anywhere in the powertrain system can cause intermittent problems and trigger the reduced engine power mode.
* PCM Issues: While less common, a problem with the PCM itself can also cause this message.
Important Note: The "Reduced Engine Power" message is not a specific diagnostic code. You must have the car scanned with an OBD-II scanner to retrieve diagnostic trouble codes (DTCs). These codes will pinpoint the likely cause of the problem, allowing for accurate diagnosis and repair. Attempting to fix the problem without knowing the specific codes can lead to wasted time and money.
