TSBs

Water Leak Reduces Chevy Express Power

Sept. 29, 2021

This bulletin applies to 2018 and prior Chevy Express H1500 vehicles.

This bulletin applies to 2018 and prior Chevy Express H1500 vehicles. Some customers may comment about an intermittent MIL being illuminated with a message that displays “reduced engine power.” This condition may be caused by water intrusion into the instrument panel to the 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 DTC P2138.

Note that aftermarket equipment can potentially generate this same code. 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.

Inspect for a water leak in the area and repair as needed.

About the Author

Mike Mavrigian | Motor Age Editor

Mike Mavrigian has written thousands of automotive technical magazine articles involving a variety of specialties, from engine building to wheel alignment, and has authored more than a dozen books that crisscross the automotive spectrum. Mike operates Birchwood Automotive, an Ohio shop that builds custom engines and performs vintage vehicle restorations. The shop also features a professional photo studio to document projects and to create images for articles and books.

About the Author

Information courtesy of Mitchell 1

Information for Technical Service Bulletins comes from ProDemand, Mitchell 1's auto repair information software for domestic and import vehicles. Headquartered in San Diego, Mitchell 1 has provided quality repair information solutions to the automotive industry since 1918.