P0122Throttle/Pedal Position Sensor/Switch A Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- Sensor A is, in practice, throttle position sensor 1 at the throttle body; the accelerator pedal has its own codes (P2120 onwards). With a cable-operated throttle there is a single potentiometer (about 0.5 V closed to 4.5 V wide open). Electronic throttles have two sensors sharing a 5 V reference and ground, usually running in opposite directions – on GM throttle sensor 1 falls from 3–4 V at idle to below 1 V at full throttle. P0122 means the signal voltage of sensor A is below its lower limit – electrically meant, not 'throttle closed': typically an open or grounded signal wire or a missing 5 V reference. Limits: Ford below 0.25 V (detected within 1 s), Saab/GM 2011 below 0.3 V for 1 s, Saab cable system below 0.2 V for 5 s. GM treats it as a one-trip fault and switches to reduced engine power; Ford lights the MIL and wrench lamp and continues on the remaining sensor or in limp mode.
- What you may notice
- Check engine light, on electronic throttles also wrench lamp
- Limp mode with reduced power ('Reduced Engine Power') on electronic throttles
- Engine barely responds to the pedal or stalls at idle
- High idle, A/C switched off (cable systems)
- Likely causes
- LikelySignal wire open or shorted to ground
- LikelyConnector at the throttle body loose or corroded
- Possible5 V reference missing (open, or shorted by another sensor)
- PossibleSensor or throttle body faulty
- RareEngine control module faulty
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €20 – €450
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.