P0122Powertrain
Powertrain · SAE
Throttle/Pedal Position Sensor A Circuit Low
Meaning
The throttle position sensor signal voltage is too low for the expected range. This is often caused by a short to ground, an open circuit or a failed sensor.
Common causes
- Faulty TPS or throttle body
- Signal wiring shorted to ground or open
- Missing 5 V supply voltage at the sensor
- Corroded connector or loose pins
- Faulty reference ground
Symptoms
- Limp mode with heavily reduced power
- Poor or absent acceleration
- Stalling or unstable idle
- No or erratic throttle response
- Check-engine light on
Severity
Moderate: the vehicle often limits power for safety, making driving difficult but still controllable.
What to do
- Read the live TPS voltage and check whether it is stuck low
- Confirm the 5 V supply and ground are present at the connector
- Inspect the signal wiring for a short to ground or an open circuit
- Replace the sensor/throttle body if faulty and perform the adaptation