What does it mean?
P1171 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Electronic Throttle System Circuit Malfunction (Open) .
Symptoms
- Check engine light on, often with the throttle warning indicator
- Engine drops into limp mode with the throttle held at a fixed low opening
- Severely reduced power, the vehicle will barely accelerate
- Idle speed high or erratic, or the engine stalls when coming to a stop
- Cruise control disabled
- Fault may clear temporarily after an ignition cycle and then return
Likely causes
- Broken or corroded wire between the throttle body and the engine control module
- Throttle body connector not fully seated, latch broken, or a terminal pushed out of its housing
- Open winding in the throttle actuator motor or in one of the throttle position sensor tracks
- Blown fuse or open supply feed to the throttle control circuit
- Water or road salt corrosion inside the throttle body connector, common on units mounted low in the engine bay
- Damaged harness section where it flexes with engine movement
- Failed throttle driver stage inside the control module
How to fix it
- Read all codes and freeze frame data, then check whether the fault is constant or intermittent
- Unplug the throttle body connector and inspect both halves for corrosion, water, bent or recessed terminals
- Measure the throttle motor winding resistance and both position sensor track resistances across the connector
- With the ignition on, check for the reference voltage and ground at the harness connector
- Perform a continuity test on each throttle circuit from the connector back to the module pin, wiggling the harness while measuring
- Check the fuse and any relay feeding the throttle control circuit
- Repair the open wiring, clean and re-tension terminals, then carry out the throttle relearn procedure and confirm the pedal-to-throttle response in live data