Code Definition

P1120 — Throttle Position Sensor out of range (low)

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

About P1120

P1120 is a manufacturer-specific powertrain diagnostic trouble code recorded for Ford 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

The P1120 code sets when the PCM detects the Throttle Position Sensor (TPS) signal voltage persistently below its calibrated minimum, typically under about 0.39V, even with the throttle not fully closed. The TPS is a potentiometer fed by a 5V reference, and its signal should rise smoothly from around 0.5 to 0.9V at closed throttle up to about 4.5V at wide open throttle. A persistently low signal makes the PCM believe the throttle is closed regardless of the actual plate or pedal position, which commonly points to a short to ground, an open reference, or a failed sensor. The driver may notice p...

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