Code Definition

P0120 — Throttle Pedal Position Sensor/Switch A Circuit Malfunction

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

About P0120

P0120 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 P0120 is stored, the module has detected 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 P0120 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 P0120 code indicates a malfunction in the circuit of the Throttle Pedal Position Sensor/Switch A. This sensor is responsible for measuring the position of the throttle pedal and relaying this information to the Engine Control Module (ECM). The ECM uses this data to adjust the air intake and fuel mixture for the engine. A malfunction in this sensor's circuit can lead to issues with engine performance, such as erratic acceleration, engine stalling, or a lack of power.

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