How to reset reduced engine power light

The "Reduced Engine Power" light signals an issue affecting engine performance, often due to a faulty throttle body, mass airflow sensor, accelerator pedal position sensor, or wiring problems.

Step 1: Diagnose the Problem

Use an OBD-II scanner to retrieve diagnostic trouble codes (DTCs) from the ECM. Common causes include throttle body issues, mass airflow sensor failure, ECM software glitches, or loose wiring.

Step 2: Fix the Underlying Issue

Depending on the code, you may need to clean or replace the throttle body, check and replace the mass airflow sensor, inspect and repair damaged wiring, or update the ECM software.

Step 3: Reset the Warning Light

Method 1: Using an OBD-II Scanner

1. Plug the scanner into the diagnostic port (usually under the dashboard). 2. Turn the ignition to ON (without starting the engine). 3. Use the scanner to clear the codes from the ECM. 4. Restart the car to check if the light is gone.

Method 2: Disconnecting the Battery

1. Turn off the engine. 2. Disconnect the negative battery terminal for 15–30 minutes. 3. Press and hold the brake pedal for 10–15 seconds to discharge remaining power. 4. Reconnect the battery and restart the car.

Method 3: Let the ECM Relearn

After fixing the issue, drive the car for 30–50 miles under normal conditions. The ECM may automatically reset the light if the problem is resolved.

Step 4: Monitor for Recurrence

If the Reduced Engine Power light returns, re-scan for trouble codes. Persistent issues may require professional diagnosis. Need help interpreting OBD-II codes?