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P2104: Throttle control system: forced idle

The ECU has held the engine at idle because it has found a fault in the electronic throttle system. The real fault is usually in another stored code.

Code P2104 at a glance
CodeP2104
SystemEngine and transmission
GroupP21xx, Throttle, injection and emissions
TypeGeneric: it means the same on every make
Can you keep driving?Better not

What P2104 means

When the ECU detects a serious fault in the electronic accelerator (pedal, throttle or its control), it protects itself by putting the engine into a safety mode. This code is not the fault itself: it tells you the ECU has held the engine at idle and is ignoring the pedal. The real cause usually shows up as another code stored at the same time.

Most common causes

  • Another code stored at the same time, which is the real explanation (pedal or throttle sensors, throttle motor)
  • Loose or corroded throttle body or pedal connector
  • Carbon on the throttle plate slowing it down
  • Low battery voltage or loose battery terminals
  • A faulty pedal sensor or throttle body
  • A fault in the engine ECU, which is uncommon

Symptoms

  • Engine or throttle warning light on
  • The engine stays at idle even when you press the pedal
  • The car barely moves

Can you drive with P2104?

Better not With the engine stuck at idle there is not enough power to drive safely in traffic. Pull over somewhere safe and call for assistance or move it to a garage carefully.

How to check it

Read every stored code, not just this one, and note them down before clearing anything: the other code tells you which part is at fault. If only this one appears, check the battery and the pedal and throttle connectors.

How to read and clear P2104 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 P2104 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

P2104 is a generic code, so it means the same on any make, for example on Audi, Fiat, Mazda, Peugeot, Toyota, Volkswagen. See what Final OBD does on your car in makes and models.

What does code P2104 mean?

When the ECU detects a serious fault in the electronic accelerator (pedal, throttle or its control), it protects itself by putting the engine into a safety mode. This code is not the fault itself: it tells you the ECU has held the engine at idle and is ignoring the pedal. The real cause usually shows up as another code stored at the same time.

Can you drive with P2104?

With the engine stuck at idle there is not enough power to drive safely in traffic. Pull over somewhere safe and call for assistance or move it to a garage carefully.

How do you clear P2104?

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, P2104 comes back.