1999 Nissan Quest P1705 and P0325 Fault: Throttle Position Sensor and Knock Sensor Issues
I'm experiencing both P1705 (Throttle Position Sensor Circuit) and P032-5 (Knock Sensor Bank 1 Circuit) codes simultaneously on my 1999 Nissan Quest. The vehicle runs fine under normal conditions, but it struggles to start—requiring a significant amount of gas to begin running. I've checked the wiring and found no visible faults. Are there any other potential causes besides replacing the throttle position sensor or knock sensor? Any insights from experienced users would be greatly appreciated.
The most likely cause is a partially faulty Throttle Position Sensor (TPS) with an open circuit at the idle position. This occurs because the idle position has the highest electrical resistance in the sensor's micro-winding. The P0325 code may be a 'ghost' reading caused by a lean condition leading to pre-ignition knock, which the Engine Control Module (ECM) cannot correct through standard timing adjustments due to its programming limitations. If you're not experienced with TPS calibration, swapping in a used throttle body is the simplest fix. Note that if your throttle body has round mounting holes, it's fixed-position and requires no recalibration. The sensor is located directly opposite the throttle cable inside the throttle body and typically comes with a 3- to 5-wire connector.