Reduced Power and Check Engine Light on GMC Sierra 3500 HD

The GMC Sierra 3500 HD uses a throttle position sensor (TPS) which commonly fails and causes:

• Check engine light illumination
• Reduced Power message
• OBD trouble code P2135

This issue is related to the throttle position sensor, and can be caused by faulty wiring to the TPS, bad connection at the TPS, or a failed TPS.

To correct this issue, the wiring harness, connector, and throttle position sensor must be inspected, tested, and/or replaced. The most common cause is a faulty TPS.