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P2100 – Throttle Actuator Control Motor Circuit/Open (OBD2)

P2100 means "Throttle Actuator Control Motor Circuit/Open". The control unit sees an open circuit: the electrical connection to the electronic throttle body is interrupted, so no current can flow when the component is commanded or read.

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P2100 quick summary

Fault codeP2100
MeaningThrottle Actuator Control Motor Circuit/Open
SystemPowertrain (Engine & Transmission)
VehiclesGeneric OBD2
SeverityHigh
Can I drive?Only carefully. The car may be in limp mode with very little power, or the engine may stall. Avoid overtaking and motorways until it is repaired.
Repair cost€0 – €600

How the electronic throttle (drive-by-wire) works

The electronic throttle body opens the throttle valve with an electric motor on command from the engine control unit; these codes mean the throttle motor, its control or its monitoring has a fault, or the control unit has forced a safety mode.

On drive-by-wire engines there is no cable between the accelerator pedal and the throttle. The pedal sensors tell the control unit what the driver wants, and the control unit drives a small DC motor in the throttle body against a return spring. Two throttle position sensors report the actual valve position back.

Because the throttle controls engine power, the system is monitored very strictly. If the commanded and actual positions disagree, the motor draws the wrong current or the valve sticks, the control unit stores a code and switches to a safety mode: forced idle, limited power, limited rpm or even engine shutdown (P2104–P2110). The EPC or Check Engine light comes on.

Common causes are carbon build-up around the throttle valve, a worn motor or gears in the throttle body, corroded connectors, water ingress, a weak battery and a throttle adaptation that was not performed after cleaning or replacement.

Symptoms of P2100

  • EPC or Check Engine light on
  • Limp mode – the car barely accelerates
  • Idle too high, too low or unstable
  • Engine stalls or hesitates
  • Delayed response to the accelerator pedal

Most common causes of P2100 (most likely first)

Mechanic's Pro Tip

Never push a drive-by-wire throttle valve open with your finger while the ignition is on – the motor can be damaged. Clean it with the ignition off and always run the adaptation afterwards.

  1. 1.Unplugged, loose or corroded connector

    Most likely

    Often after previous repair work in the area.

  2. 2.Broken wire in the harness

    Typical at bends, near the engine mounts and where the harness rubs on brackets.

  3. 3.Burnt-out winding or internal break in the electronic throttle body

  4. 4.Dirty or sticking throttle valve

    Carbon deposits stop the valve from closing or moving smoothly.

  5. 5.Worn throttle motor, gears or position sensor

    The throttle body is usually replaced as a unit.

  6. 6.Throttle adaptation not performed after cleaning, replacement or battery disconnection

  7. 7.Low battery voltage or poor ground

    The motor needs a stable supply; voltage dips set throttle codes.

Step-by-step diagnostic guide

  1. 1

    Read codes and throttle data

    Read all codes and compare commanded and actual throttle angle and both throttle sensor signals in live data with the ignition on and the engine idling.

  2. 2

    Measure resistance and continuity

    Unplug the electronic throttle body and measure its resistance across the terminals. An infinite (OL) reading confirms an internal break. If the component is fine, check each wire back to the control unit for continuity.

    Multimeter: Solenoids and heaters typically read a few ohms to a few dozen ohms; "OL" means open. Wire continuity: below about 1 Ω.

  3. 3

    Inspect and clean the throttle

    With the ignition off, remove the intake hose and check the throttle valve for carbon. Clean it with throttle cleaner without forcing the valve open by hand against the motor.

  4. 4

    Check connector, supply and ground

    Check the throttle connector for corrosion and measure the motor control and sensor supply.

    Multimeter: Throttle position sensors: 5 V reference; signals usually moving in opposite directions or with a fixed offset (for example about 0.5–4.5 V).

  5. 5

    Run the throttle adaptation

    Run the throttle body adaptation (basic setting) with the scan tool – ignition on, engine off, pedal not pressed.

  6. 6

    Replace and adapt

    If the adaptation fails or the motor does not follow the command, replace the throttle body and run the adaptation again.

Frequently asked questions

Can I keep driving with P2100?

Only carefully. The car may be in limp mode with very little power, or the engine may stall. Avoid overtaking and motorways until it is repaired.

How much does it cost to fix P2100?

Typical repair costs are 0 € – 600 €, depending on the cause and the vehicle. The most common fixes are: unplugged, loose or corroded connector; broken wire in the harness; burnt-out winding or internal break in the electronic throttle body. Always confirm the cause with the tests above before buying parts.

Why does my car have no power with a throttle code?

The control unit deliberately limits power for safety when it cannot trust the throttle. Once the fault is fixed and the codes cleared, full power returns.

Can a dirty throttle body cause these codes?

Yes, especially codes for throttle performance and idle position. Cleaning plus a throttle adaptation often fixes it.

What is the difference between P2100 and similar codes?

P2100 belongs to a group of codes for the same component that differ in the type or location of the fault: P2101 – Throttle Actuator Control Motor Range/Performance; P2102 – Throttle Actuator Control Motor Circuit Low; P2103 – Throttle Actuator Control Motor Circuit High; P2104 – Throttle Actuator Control System - Forced Idle; P2105 – Throttle Actuator Control System - Forced Engine Shutdown; P2106 – Throttle Actuator Control System - Forced Limited Power. The tests on this page apply to the whole group; the type of fault tells you where to start.

Related fault codes

This guide is for information only. Working on vehicles can be dangerous — if you are unsure, have the car checked by a qualified mechanic. Values can differ between model years; always check the manufacturer's repair information.