Cause
Debris blocking sensor airflow
Leaves, insects or road debris packed against a sensor that needs air moving past it. An ambient temperature sensor, a humidity sensor or a mass airflow element all measure something about the air, and all of them assume the air is actually reaching them.
A blocked sensor reads its own surroundings instead. An ambient sensor behind a packed grille reports engine bay heat, so the module believes it is far warmer outside than it is — and the readings look entirely plausible, which is why nothing appears wrong. A reading that rises when the vehicle stops and falls when it moves is the tell.
The blockage is usually visible and free to check. Look behind the grille, at the front of the condenser, and inside the intake ducting. Compare the reading against a known ambient after an overnight soak — the two should agree closely on a cold vehicle, and a disagreement there proves an obstruction or a mounting problem rather than a failed element.
Typically an easy fix. Often worth checking before paying anyone to look.
Codes this can cause (2)
Codes where this is a likely explanation first, rather than merely a possible one.
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