P2138 Code GM Engine
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GM: Intermittent Check Engine Light, DTC P2138 With Reduced Engine Power

Some customers may comment on an intermittent malfunction indicator lamp (MIL) being illuminated with a message or an indicator that displays Reduced Engine Power. The technician may observe on a scan tool DTC P2138 – Accelerator Pedal Position (APP) Sensor 1-2 Correlation set as Current or in History.

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Models

2005-2015 GM Passenger Cars and Light-Duty Trucks

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This bulletin has been revised to add model years, update the labor operations to the Global Labor Code (GLC) and to remove the Warranty Information (Saab U. S. Models) section. Please discard Corporate Bulletin Number 07-06-04-019D.

Condition

Some customers may comment on an intermittent malfunction indicator lamp (MIL) being illuminated with a message or an indicator that displays Reduced Engine Power.

The technician may observe on a scan tool DTC P2138 – Accelerator Pedal Position (APP) Sensor 1-2 Correlation set as Current or in History.

Cause

This condition may be caused by water intrusion into the instrument panel (IP) to body harness connector, which carries the APP sensor signals to the ECM/PCM. This water intrusion results in a voltage difference between APP Sensor 1 and APP Sensor 2 that exceeds a predetermined value for more than a calibrated period of time, setting P2138.

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Correction

NOTE: Aftermarket equipment can generate DTC P2138 and/or other DTCs.

1. Verify that aftermarket equipment is not electrically connected to any of the APP sensor signal or low reference circuits or to any other ECM/PCM 5V reference or low reference circuits.

2. Perform the Diagnostic System Check – Vehicle.

   a. If any 5V reference DTCs are set, refer to Diagnostic Trouble Code (DTC) List – Vehicle.

   b. If any 5V reference DTCs are not set, proceed to Step 3.

3. Locate the IP to body harness connector, which may be located in and around the left hand kick panel area or inside the IP.

NOTE: Some examples of potential water leaks are: A-pillar seals, sunroof drain lines (if equipped) and windshield/cowl sealing.

4. Inspect for a water leak in the area. If necessary, use a water hose to determine the source of the leak.

   a. If a water leak is observed, repair as necessary. Verify the effectiveness of the repair.

5. Inspect the IP to body harness connector terminals for corrosion and debris.

   a. If any corrosion and/or debris is observed, repair as necessary.

6. After completing the repair, verify the proper operation of the system.

Courtesy of ALLDATA.

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