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P2122: Throttle or pedal position sensor D circuit low

The ECU sees too low a voltage from sensor D, almost always on the accelerator pedal. Usually a wire shorted to ground, the connector or the sensor.

Code P2122 at a glance
CodeP2122
SystemEngine and transmission
GroupP21xx, Throttle, injection and emissions
TypeGeneric: it means the same on every make
Can you keep driving?With care

What P2122 means

An electronic accelerator pedal has two sensors that measure how far you press it, and the ECU compares them so it never relies on just one. On most cars the letters D and E refer to these pedal sensors, although each manufacturer assigns the letters. This code means the signal from sensor D is below the possible range, almost always due to an electrical fault.

Most common causes

  • Loose, dirty or corroded accelerator pedal connector
  • A sensor wire broken or chafed and touching ground, or the 5 V supply lost
  • A floor mat or object pressing on the pedal or its wiring
  • A worn pedal sensor (usually the whole pedal unit is replaced)
  • A fault in the engine ECU, which is uncommon

Symptoms

  • Engine or throttle warning light on
  • Reduced power or limp mode
  • Poor or jerky response to the pedal
  • Slightly high idle

Can you drive with P2122?

With care You can usually drive with care, as the ECU falls back on the other sensor, but with little power. See a garage soon: if the second sensor fails too, the engine drops to idle.

How to check it

Use a live data reader to watch both pedal signals while pressing the pedal slowly: they should rise smoothly and in step, with no jumps. If the sensor D signal freezes or jumps, the fault is on that side.

How to read and clear P2122 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 P2122 with this same explanation and whether it’s confirmed, pending or permanent.

With Free you read this code with its short description for nothing, and clear it if the engine stores it over standard OBD. With Pro you get the full explanation, how the car was running when it was logged (revs, temperature, load) and clearing in every control unit.

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 the ITV. It’s all in how to read and clear fault codes and in the ITV and OBD.

Similar codes

P2122 is a generic code, so it means the same on any make, for example on Alfa Romeo, Dacia, Jeep, Kia, Nissan, Škoda. See what Final OBD does on your car in makes and models.

What does code P2122 mean?

An electronic accelerator pedal has two sensors that measure how far you press it, and the ECU compares them so it never relies on just one. On most cars the letters D and E refer to these pedal sensors, although each manufacturer assigns the letters. This code means the signal from sensor D is below the possible range, almost always due to an electrical fault.

Can you drive with P2122?

You can usually drive with care, as the ECU falls back on the other sensor, but with little power. See a garage soon: if the second sensor fails too, the engine drops to idle.

How do you clear P2122?

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, P2122 comes back.