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DTC codes / P21xx · Fuel and air metering / P2100

P2100Throttle Actuator Control Motor Circuit/Open

P2100 indicates that the powertrain control module (PCM) has detected an open circuit or excessive resistance in the wiring that supplies power or ground to the electronic throttle actuator motor. The PCM commands the throttle plate to move, but the electrical path to the motor is broken, so the motor cannot respond and the PCM sets this code.

SystemPowertrain
Code typeGeneric (all makes)
SeverityHigh
Fix difficultyIntermediate
AreaFuel and air metering

Symptoms you may notice

  • Illumination of the check engine light, often accompanied by the electronic throttle control (ETC) warning light.
  • The engine may enter limp-home mode, limiting speed to a low threshold such as 20–30 mph.
  • The accelerator pedal may feel unresponsive or the engine may idle at an elevated speed.
  • In some vehicles, the engine may crank but not start because the throttle plate is held at a default position.
  • Often no symptoms besides the warning light if the open circuit is intermittent and the throttle still operates normally.
  • A noticeable delay or hesitation when pressing the accelerator pedal before the engine responds.

Common causes, most likely first

  1. Broken, chafed, or corroded wires in the throttle actuator motor circuit, especially at the connector or where the harness flexes.
  2. A faulty throttle body assembly with an open winding in the actuator motor or a failed internal connection.
  3. Corroded or loose pins in the throttle body electrical connector or the PCM connector.
  4. A blown fuse or relay that supplies power to the throttle actuator motor circuit.
  5. Water intrusion into the throttle body connector or harness, leading to corrosion and an open circuit.
  6. A failed PCM driver for the throttle motor circuit, though this is less common than wiring or throttle body faults.

How to diagnose and fix it

  1. Inspect the throttle body connector and wiring for corrosion, loose pins, or chafed insulation, and repair as needed.
  2. Check the fuse and relay that supply power to the throttle actuator motor circuit and replace any failed components.
  3. Disconnect the throttle body connector and measure resistance across the actuator motor terminals; compare to the manufacturer's specification to confirm an open winding.
  4. Perform a voltage drop test on the power and ground circuits to the throttle motor while commanding the throttle with a scan tool.
  5. If the wiring and power supply are good, replace the electronic throttle body assembly and perform a throttle relearn procedure with a scan tool.
  6. Clear the diagnostic trouble codes and verify the repair by running the throttle through its full range with a scan tool and test-driving the vehicle.

What a P2100 often hides

  • A P2100 can be set by a completely dead battery or a voltage spike during jump-starting, so always check battery health and clear the code to see if it returns before replacing parts.
  • The throttle actuator motor circuit is separate from the throttle position sensor circuits, so a P2100 does not automatically mean the throttle body is bad; the wiring is the more frequent culprit.
  • On many vehicles, the throttle body connector sits low on the engine and is exposed to road splash, making water intrusion and corrosion a common hidden cause of an open circuit.
  • A faulty brake pedal switch or a mismatch between the two accelerator pedal position sensors can cause the PCM to disable the throttle motor and set a P2100 as a secondary code, so scan all modules for related codes.
  • After replacing the throttle body, a throttle relearn or idle relearn procedure is mandatory on most vehicles; skipping it can cause a repeat P2100 or poor idle quality.

Can I keep driving with P2100?

Do not drive the vehicle with an active P2100 because the engine may enter limp-home mode without warning, limiting speed and creating a safety hazard. If the code is intermittent and the throttle responds normally, drive only to a repair shop at low speed and avoid highways.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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