Happened twice now, both times just after starting up cold. 'check engine' flashes a couple of times, then goes out and stays out for the rest of the journey. Diagnostic says '22' Knock Sensor. Question is, since the check engine goes out, is the knock sensor just intermittent or pemanently faulty? Coincidentally happened just after filling with V-formula for the first time which seemed to be dramatically better than the usual Optimax (or am I imagining things?).

Graham

 

If the light is not on with the engine running then the fault is intermittant and could be quite hard to track the cause , knock sensor is meant to retard the ignition to a point when ' knock ' is no longer there . If this happens regular on startup the sensor is doing it's job on hearing knock and should move the timing to stop it , but however if something is causing the noise in the engine i.e smallend bearing etc then that's got to be sorted to stop the eml from coming on as when the timing gets moved and the noise does'nt go the the ecu will think the knock sensor is faulty and put the light on. On the other hand knock sensor may be to sensitive !