P2120: Throttle or pedal position sensor D circuit fault
The ECU gets a faulty signal from sensor D, almost always one of the accelerator pedal sensors. Usually the connector, a wire or the sensor.
| Code | P2120 |
|---|---|
| System | Engine and transmission |
| Group | P21xx, Throttle, injection and emissions |
| Type | Generic: it means the same on every make |
| Can you keep driving? | With care |
What P2120 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 invalid or has been lost, almost always due to an electrical fault.
Most common causes
- Loose, dirty or corroded accelerator pedal connector
- A sensor wire broken, chafed or with a poor contact
- 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 P2120?
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.
Open the bonnetthe in-depth explanation
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 P2120 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 P2120 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
- P211C The throttle actuator B control motor current gives readings outside the normal
- P211D The electronic throttle body B gives readings outside the normal range
- P211E The throttle actuator B control unit processor is not working properly
- P211F The throttle actuator B control unit gives readings outside the normal range
- P2121 Throttle or pedal position sensor or switch D operates outside its expected
- P2122 Throttle or pedal position sensor D circuit low
- P2123 Throttle or pedal position sensor D circuit high
- P2124 Circuit D of the throttle or pedal position sensor or switch fails
- P2100 Throttle actuator A control motor circuit open
- P2101 Throttle actuator A control motor circuit range or performance
- P2102 Throttle actuator A control motor circuit low
- P2104 Throttle control system: forced idle
What does code P2120 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 invalid or has been lost, almost always due to an electrical fault.
Can you drive with P2120?
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 P2120?
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, P2120 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.
