2004 Trailblazer 4.2L - P1516, P2101, P0171 Fault Codes at 130,000 Miles: Solutions & Diagnosis
My 2004 Chevrolet Trailblazer 4.2L engine is showing fault codes P0171, P1516, and P2101 at approximately 130,000 miles. The vehicle exhibits poor fuel economy and hesitation during acceleration. I'm seeking reliable advice on diagnosing and resolving these issues. P0171: System Too Lean (Bank 1) P1516: Throttle Actuator Control (TAC) Module - Throttle Actuator Position Performance P2101: TAC Module Position Performance Common causes include vacuum leaks, low fuel pressure, and electrical faults in the throttle actuator control (TAC) module. I've already checked basic systems such as fuel pressure and vacuum lines, but the issue persists. Any insights into troubleshooting or repair steps would be greatly appreciated.
P0171 indicates a lean air-fuel mixture in Bank 1, which can stem from intake leaks or faulty sensors. P1516 and P2100 both point to issues with the Throttle Actuator Control (TAC) module — specifically its throttle actuator position performance. These codes often result from internal TAC faults or wiring problems. Recommended steps: Inspect for vacuum leaks, verify fuel pressure is within specifications, and check the TAC module and its associated electrical circuit for damage or corrosion.