P0122 Throttle/pedal position sensor A circuit low
What P0122 means
The voltage from throttle position sensor A is lower than the engine computer considers possible. The computer cannot tell how far the throttle is open and normally switches to limp mode with very limited power.
P0122 is a generic SAE J2012 code: it means the same on every make. The exact cause still depends on the car, so read the freeze-frame data before replacing parts.
At a glance
- Severity
- High
- Typical repair cost
- 60–500 €
- Workshop time
- 0.5–2.5 h
- Repair difficulty
- Medium
- DIY possible
- Yes
- Check engine light
- Yes
- Affects emissions test
- Yes
- Limp mode possible
- Yes
Parts and labour at an independent workshop in Europe. Main dealers charge more; the cause decides the bill, not the code.
Symptoms
- Check engine light on
- Limp mode with very little power
- Engine may idle only or respond poorly to the pedal
- Possible stalling
Common causes
- Failed throttle position sensor (usually inside the throttle body)
- Open circuit in the 5 V reference wire
- Signal wire shorted to ground
- Unplugged or corroded connector
Can I keep driving with P0122?
Get it to a workshop urgently. In limp mode the car accelerates very slowly, which is unsafe on fast roads.
What to check first
- Check that the throttle body connector is fully plugged in and clean.
- Measure the 5 V reference and ground at the connector with the key on.
- Check the signal wire for a short to ground with the connector unplugged.
- If wiring is good, replace the throttle body (or sensor) and run the throttle adaptation.
Related codes
- P0121 Throttle/pedal position sensor A range/performance
- P0123 Throttle/pedal position sensor A circuit high
- P0120 Throttle/pedal position sensor A circuit
- P0125 Insufficient coolant temperature for closed-loop fuel control
- P0128 Coolant thermostat: coolant temperature below regulating temperature
- P0118 Engine coolant temperature sensor 1 circuit high
- P0117 Engine coolant temperature sensor 1 circuit low
- P0116 Engine coolant temperature sensor 1 range/performance
Data: TORKO fault-code catalogue, built on OBDex (CC0-1.0) and reviewed against workshop practice. Informational only — it does not replace a diagnosis by a mechanic.
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