Code Definition

P2109 — Throttle / Pedal Position Sensor A Minimum Stop Performance

System: Powertrain  |  Type: Generic (OBD-II Standard)  |  Make: Toyota

About P2109

P2109 is a generic (obd-ii standard) powertrain diagnostic trouble code recorded for Toyota vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P2109 is stored, the module has detected a plausibility fault — the measured value is in the electrical range but is not consistent with expected operating behaviour; and a sensor-related fault — the reported value from the named sensor is out of spec.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

Because P2109 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

The engine control module runs a learning routine that records the throttle position sensor voltage corresponding to the fully closed throttle plate, known as the minimum or lower mechanical stop. That learned value becomes the zero reference for every subsequent throttle position calculation, so airflow, idle control, and pedal response all depend on it being accurate. DTC P2109 sets when the module carries out this routine and finds the closed throttle reading sits outside the expected window, meaning the plate is not returning to the position the module expects or the sensor is no longer re...

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