What this code means

The PCM detected that the throttle actuator (electronic throttle body) position does not match the commanded position. This code triggers the "Reduced Engine Power" warning, which is one of the most dreaded issues on GM trucks and SUVs. The vehicle may be limited to very low speeds.

Symptoms

• Reduced Engine Power message (most prominent)
• Check Engine Light
• Severely limited throttle response
• Vehicle may not accelerate past 15-20 mph
• Limp mode
• Poor idle quality

Common causes

• Faulty throttle body motor or TPS
• Carbon buildup restricting throttle blade movement
• Throttle body wiring harness damage
• Corroded throttle body connector
• PCM software issue requiring reflash
• TAC module failure
• Intermittent connection at throttle body

Diagnostic steps

1. Monitor commanded vs actual throttle position with scan tool
2. Inspect throttle body for carbon buildup
3. Check throttle body wiring harness for damage
4. Test throttle body motor resistance
5. Verify 5-volt reference and ground circuits
6. Check for PCM software updates/TSBs

Repair notes

Clean throttle body thoroughly. If cleaning does not help, replace throttle body assembly. Check for PCM reflash TSBs. Commonly seen on Silverado, Tahoe, Sierra, Yukon, and Trailblazer.

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