Code Definition

P2122 — Throttle / Pedal Position Sensor / Switch D Circuit Low Input

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

About P2122

P2122 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 P2122 is stored, the module has detected a signal or supply voltage lower than the expected operating range; 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 P2122 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

Accelerator pedal position sensor D forms part of the redundant sensor set that tells the engine control module how far the driver is pressing the pedal in a drive by wire system. The module supplies the sensor with a regulated reference voltage and expects the returned signal to sit at a defined low voltage with the pedal released, rising smoothly and proportionally as the pedal is depressed. DTC P2122 sets when the module measures that signal below the minimum valid threshold, typically under about 0.2V, which points to a short to ground, an open reference supply, or a sensor whose output ha...

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