P0122 — Throttle/Pedal Position Sensor/Switch "A" Circuit Low Input

What it means

The voltage on the signal line of throttle position sensor A has fallen below the calibrated threshold, typically under about 0.2 V, and stays there regardless of pedal movement. The ECM therefore reads a permanently closed throttle and cannot calculate driver demand correctly. The result is a lit MIL, forced idle or limp-home mode, no response to the accelerator pedal and, on some vehicles, an engine that will start but not rev.

Likely causes (most common first)

1. Signal wire shorted to ground or to the sensor ground circuit
2. Open circuit in the 5 V reference feed to the sensor
3. Internally failed throttle or pedal position sensor
4. Water, dirt or corrosion bridging the terminals in the connector
5. Damaged wiring at a chafe point behind the throttle body or pedal bracket
6. Faulty engine control module output

Can you drive with it?

Driving is barely possible because the engine stays at idle power, so the car should be repaired or towed rather than used.