PO122 Throttle Position Sensor Code - 2000 Pontiac Montana 3.4L Diagnosis and Solutions
I'm experiencing symptoms of a faulty throttle position sensor (TPS) along with the PO122 diagnostic code on my 2000 Pontiac Montana 3.4L. I replaced the TPS and cleared the code, but the vehicle is still running poorly despite the code not returning. The engine feels sluggish, responds slowly to throttle input, and exhibits rough idle. I've confirmed that the wiring and connections between the PCM and TPS are intact. Can anyone suggest further troubleshooting steps or potential causes for this persistent performance issue?
Can you graph the TPS signal using your OBD2 scanner? If so, perform a KOEO (Key On, Engine Off) test by stepping on the gas pedal fully and then releasing it. The TPS voltage should show a smooth rise and fall with a maximum reading around 4.5 volts. Make sure to verify that the circuit connections from both the PCM and TPS are secure and free of corrosion. Could you also clarify what 'running terrible' specifically means—such as hesitation, stalling, or poor acceleration? Any updates on your findings would be greatly appreciated.