Code Definition

P0122 — Throttle/Pedal Position Sensor/Switch A Circuit Low Input

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

About P0122

P0122 is a generic (obd-ii standard) powertrain diagnostic trouble code. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P0122 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 P0122 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 P0122 fault code is triggered when the Engine Control Module (ECM) detects an abnormally low voltage input from the Throttle Position Sensor (TPS) or Accelerator Pedal Position (APP) Sensor in the 'A' circuit. This low voltage condition suggests that the signal from the sensor is below the expected range, which can be due to a short to ground, a faulty sensor, or an issue in the circuitry. This condition is continuously monitored by the ECM and will set the fault code when the low voltage criteria are met during engine operation.

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