Code Definition

P1120 — Accelerator Pedal Position Sensor Circuit

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

About P1120

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

This DTC sets when the Engine Control Module (ECM) detects an abnormal voltage signal from the Accelerator Pedal Position (APP) sensor circuit. The APP sensor is typically built from two potentiometer or hall effect tracks that send separate voltage signals corresponding to pedal position, giving the ECM a redundant reading it can cross check. The ECM monitors both signals for consistency and correct range, and if the primary signal from APP Sensor 1 falls out of specification or deviates excessively from the second signal, P1120 is logged. When this code sets the vehicle commonly enters a red...

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