Code Definition

P1120 — Throttle Position Sensor out of Range Low

System: Powertrain  |  Type: Manufacturer-Specific  |  Make: Mazda

About P1120

P1120 is a manufacturer-specific powertrain diagnostic trouble code recorded for Mazda vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1120 is stored, the module has detected a signal or supply voltage lower than the expected operating range; 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.

P1120 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

DTC P1120 is set when the Powertrain Control Module (PCM) sees the Throttle Position Sensor (TPS) signal voltage stay below the calibrated minimum for a valid reading. The TPS is a potentiometer fed by a 5V reference and a ground, returning a signal voltage that rises smoothly as the throttle opens, typically from around 0.5V at closed throttle to about 4.5V at wide open throttle. A signal that sits too low usually means the signal wire is shorted to ground, the reference or signal circuit is open, or the sensor has failed internally. With an invalid throttle angle the PCM may force a default ...

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