SureTrack Real Fix: Hummer of a Problem

Sometimes you don’t have diagnostic trouble codes to help you resolve a problem and you have to use your experience to guide you to a solution. Follow this Real Fix to see how the problem of lack of power on this 2006 Hummer was diagnosed and repaired.

Vehicle
2006 Hummer H3 3.5L

Title
Engine Lacks Power, Replaced Manifold Absolute Pressure Sensor

Complaint
The customer states the engine lacks power.

Cause
Confirmed the customer’s complaint and found the engine lacked power. Connected a scan tool to check for codes, but found no codes were present. Used the scan tool to monitor the live data, started the vehicle and found the manifold absolute pressure sensor signal parameter was erratic. Connected a vacuum gauge to the manifold absolute pressure sensor vacuum source hose, started the engine and found the specified vacuum was present. Visually inspected the manifold absolute pressure sensor harness and found no obvious signs of damage. Disconnected the manifold absolute pressure sensor harness connector, visually inspected the connector and terminals, but found no obvious signs of damage. Key on, engine off, used a multi-meter to check for the presence of reference voltage and ground at the manifold absolute pressure sensor harness connector and found both were present and remained stable during wiggle testing to simulate road shock. The results of these tests verified the manifold absolute pressure sensor was faulty.

Correction
Replaced the manifold absolute pressure sensor, performed a road test and verified the vehicle operated properly. The customer’s concern did not return.