P0122: Throttle or pedal position sensor A: low signal
The ECU sees a voltage that is too low from throttle or pedal position sensor A. Nearly always a wire, the connector or the sensor itself.
| Code | P0122 |
|---|---|
| System | Engine and transmission |
| Group | P01xx, Air and fuel metering |
| Type | Generic: it means the same on every make |
| Can you keep driving? | With care |
What P0122 means
The ECU needs to know how far the throttle valve (the flap that lets air into the engine) is open, or how far you are pressing the accelerator, to meter air and fuel. Which sensor counts as sensor A is decided by each manufacturer, although it is usually the throttle one. This code means the signal voltage is below what is possible, nearly always because of an electrical problem.
Most common causes
- Sensor connector loose or corroded
- Signal wire broken or shorted to earth
- Broken supply wire to the sensor
- Faulty position sensor
- Faulty throttle body (if the sensor is built in)
- Faulty engine ECU (uncommon)
Symptoms
- Engine warning light on
- The car goes into limp mode and barely accelerates
- Unstable idle or the engine stalling
- Jerking or odd response when you press the accelerator
Can you drive with P0122?
With care You can drive, but the car may suddenly lose power when it drops into limp mode. Get it to a garage soon and avoid overtaking and fast roads in the meantime.
Open the bonnetthe in-depth explanation
How to check it
Check the sensor’s position or voltage in live data with your foot off the pedal: if it reads zero or close to zero all the time, the fault is more likely in the wiring or connector than in the mechanics. Gently moving the loom while watching the value helps to find it.
How to read and clear P0122 with Final OBD
Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P0122 with its description and whether it’s confirmed, pending or permanent.
If the engine stores it over standard OBD, with FREE you read this code with its explanation for nothing and clear it. With PRO you also read the faults of every control unit and clear them in all of them.
Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before an inspection. It’s all in how to read and clear fault codes and in inspections and OBD.
Similar codes
- P011E Coolant temperature 1 and outside air temperature do not match with the engine
- P011F Coolant temperature 2 and outside air temperature do not match with the engine
- P0120 Throttle or pedal position sensor A: circuit fault
- P0121 Throttle or pedal position sensor A: out of expected range
- P0123 Throttle or pedal position sensor A: high signal
- P0124 Throttle or pedal position sensor A: intermittent signal
- P0125 Engine takes too long to warm up for fuel mixture control
- P0126 The coolant temperature is too low for stable engine operation
- P0100 Mass or volume air flow sensor circuit fault
- P0101 Air flow sensor range or performance problem
- P0102 Air flow sensor circuit low input
- P0103 Air flow sensor circuit high input
What does code P0122 mean?
The ECU needs to know how far the throttle valve (the flap that lets air into the engine) is open, or how far you are pressing the accelerator, to meter air and fuel. Which sensor counts as sensor A is decided by each manufacturer, although it is usually the throttle one. This code means the signal voltage is below what is possible, nearly always because of an electrical problem.
Can you drive with P0122?
You can drive, but the car may suddenly lose power when it drops into limp mode. Get it to a garage soon and avoid overtaking and fast roads in the meantime.
How do you clear P0122?
With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, P0122 comes back.
Read it on your car
Final OBD reads and clears engine faults through standard OBD for free, each one explained in plain English. With PRO it also reads the faults of every control unit, each make’s own codes included, and clears them in all of them.
