Cause
Faulty stop-start mode switch
The switch by which the driver disables stop-start, faulty. Its purpose is to let the driver turn the function off, and a fault reverses that control.
Reporting permanently pressed disables stop-start, so the function silently stops working and the owner assumes a fault — which is the commonest presentation and generates a great deal of unnecessary diagnosis. Reporting never pressed means it cannot be disabled, which is merely irritating. These switches are console-mounted and heavily used, so worn contacts and spilled liquid account for most failures. Watch the reported state while operating the switch — one that flickers or does not change is the fault, and a static resistance check at one position will not reveal it.
Typically a moderate job.
Codes this can cause (1)
Codes where this is a likely explanation first, rather than merely a possible one.
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