DTC codes / Toyota codes / P1121
P1121 on Toyota vehicles means the engine control module (ECM) has detected that the accelerator pedal position (APP) sensor signal is outside the expected range or is not correlating properly with the other APP sensor signal. The ECM compares the two APP sensor voltages and expects them to track together within a specific tolerance; when the relationship falls outside that window, it sets this code and often limits engine power.
Guidance is general and written for Toyota vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.
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