# What Does Implausible Signal Mean?



## DCCD (Sep 5, 2011)

Hi, i got an error code (P0221) for this sensor (G188),.

My question is what does (implausible signal) mean? and how the ECU know that the signal was implausible?

Which sensor does the ECU read to match the data? is it (G187) sensor?


Thanks in Advance


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## BassNotes (Mar 16, 2005)

An implausible signal is one that is ambiguous, out of range, or otherwise faulty that the ECU or other controller can't make out an actual value from.

The ECU expects a signal from the angle sensor on your engine's throttle actuator. IIRC, the angle sensor is an arc of resistive material with a DC voltage across it, and a wiper linked to the throtlle moves across it when the throttle plate moves (i.e., it's a potentiometer). Therefore, the DC voltage on that wiper relates proportionally to the angle of the throttle, and that's what the ECU reads. That's how the ECU knows it has moved the throttle to the right position.

If the potentiometer or its wiring is faulty, the signal to the ECU will not make sense. The throttle might or might not be in the correct position, but it has no way to confirm. And then your ECU reports an implausible signal and throws the code.


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