What does it mean?
P1224 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Throttle/Pedal Position Sensor/Switch B Sensor Voltage Out of Range .
Symptoms
- Check engine lamp on, frequently with the vehicle in limp mode
- Poor or erratic throttle response, surging or a flat spot when accelerating
- High, low or hunting idle
- Cruise control disabled
- Automatic transmission shifting harshly or at the wrong points because it uses the same load signal
Likely causes
- Worn or scored resistive track inside the throttle position sensor
- Loss or drift of the 5 volt reference, or a high resistance sensor ground
- Corroded, wet or loose terminals in the sensor connector
- Chafed signal wire shorted to ground, to another circuit or to battery voltage
- Carbon build-up in the throttle bore holding the plate away from its rest position
- Throttle body or pedal sensor that was replaced without the required relearn
- Damaged sensor input circuit inside the module
How to fix it
- Graph both throttle or pedal sensor signals while slowly opening and closing the throttle and look for a spike or dropout
- Measure the 5 volt reference and ground at the sensor connector with the ignition on
- Inspect the connector for corrosion, water and pushed-back terminals
- Check the signal wire for continuity and for shorts to ground or to battery voltage
- Clean carbon from the throttle bore and plate, then check the closed position value
- Perform the throttle and pedal relearn procedure and recheck the readings
- Replace the sensor or throttle body only after reference, ground and wiring have been verified