The P0122 code indicates that the Engine Control Module (ECM) has detected a voltage signal from the Throttle Position Sensor (TPS) that is lower than the expected minimum value. This suggests an electrical open or short in the sensor circuit, preventing the computer from accurately determining the throttle plate position.
Internal failure of the sensor's potentiometer or a short circuit within the sensor housing.
Frayed, pinched, or chafed wires causing a short to ground in the signal or reference circuit.
Oxidation or poor pin tension at the sensor connector, interrupting the electrical signal.
A sensor that has shifted physically or is improperly adjusted, sending a voltage below the allowable range.
Internal circuitry failure within the computer that processes the TPS signal.
While the sensor is the most common failure point, replacing it without testing the wiring first may not resolve the issue if the fault lies in a chafed wire or corroded connector.
No. PCM failure is very rare for this specific circuit. Most technicians erroneously suggest PCM replacement when they cannot find a wiring fault, but the issue is almost always the sensor or the harness.
The vehicle will usually start and run, but it may enter a reduced-power mode to protect the engine, making highway driving dangerous or impossible.