Dérive du capteur de position papillon ou pédale

A throttle or accelerator pedal sensor whose output has moved away from what the module was taught to expect. These are the most safety-monitored sensors on the engine, because there is no cable between the pedal and the throttle any more — the connection is entirely a number, and a wrong number means an engine producing torque nobody asked for.

Which is why both sensors are doubled. The pedal and the throttle body each carry two independent tracks, deliberately given different slopes or offsets so they can never agree by accident. The module continuously checks that the pair disagree in exactly the expected way, and drift on one track breaks that relationship long before either reading looks obviously wrong on its own.

The mechanism is usually mechanical wear on a resistive track — a worn spot at the idle position, where the wiper has rested for most of the sensor's life. That is why symptoms cluster at small openings: a hesitation just off idle, or a stumble pulling away, on a car that is fine at larger throttle openings. Contactless sensors avoid this and drift for other reasons, usually magnet ageing or heat.

Expect the response to be blunt. A failed plausibility check cuts throttle authority hard and drops the engine into a heavily limited mode — deliberately, because the alternative is unintended acceleration. Many vehicles need a throttle relearn after any repair here, and skipping it leaves the fault apparently unfixed.