Rick's Free Auto Repair Advice

P2138 Reduced Power on GM vehicles #07-06-04-019E

Updated service bulletin for P2138 Reduced Power on GM vehicles

GM 07-06-04-019E service bulletin updates repair for P2138 reduced power on GM vehicles

GM has issued a technical service bulletin # 07-06-04-019D to address a P2138 Reduced Power issue. That bulletin applied to just the vehicles listed below. However, GM has issued an updated service bulletin 07-06-04-019E that expands the vehicle list and contains additional trouble shooting techniques. The P2138 trouble code may be stored in the computer along with a check engine light. The previous service bulletin can be found here

New vehicles affected list

ALL 2005-2015 GM Passenger Cars and Light Duty Trucks

Previous vehicles affected

2005-2011 GM Passenger Cars and Light Duty Trucks (Including Saturn)

2005-2009 HUMMER H2

2006-2010 HUMMER H3

2005-2009 Saab 9-7X

The P2128 trouble code refers to Accelerator Pedal Position (APP) Sensor 1-2 Correlation.

accelerator position sensor, P2138, position transducer

Accelerator pedal position sensor assembly

Do NOT assume you have a bad accelerator pedal sensor. GM says the condition is caused by water leaking into the body harness connector that carries the APP signal to the PCM. The water changes the voltage readings from the APP.

However, this code can also be generated by the installation of aftermarket equipment that is tapped into the wrong wire (radio, remote starter, radar detector, etc).

Locate the body harness connector, located in and around the left hand kick panel area or inside the IP (consult a shop manual for location). Water can leak into the connector from clogged sunroof drains, A-pillar leaks, or windshield or cowling leaks. If you find water in the connector, locate the source of the leak. Then dry out the connector, apply dielectric grease and reseat the connector.


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. Connect scan tool and check for trouble codes that related to any 5V reference signals.

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.

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

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.

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

6. After completing the repair, verify the proper operation of the system. Depending on the vehicle and model year, perform the

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

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