Code Definition

P1121 — Accelerator Pedal Position Sensor Range/Performance Problem

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

About P1121

P1121 is a manufacturer-specific powertrain diagnostic trouble code recorded for Toyota vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1121 is stored, the module has detected 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.

P1121 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 Engine Control Module (ECM) uses the accelerator pedal position (APP) sensor signals to determine driver throttle demand on the electronic throttle control system, cross checking the two redundant signal tracks for plausibility. DTC P1121 is set when the ECM detects that the APP signals are out of the expected range, or that the two tracks fail to correlate consistently with pedal movement, even though the circuit may not show a hard open or short. This typically results from sensor wear, signal drift, intermittent resistance, or a mechanical pedal problem. When this code is set the ECM co...

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