orangecurry

Afternoon all.

My Impreza has just started showing the CEL, about two/three minutes into a journey from cold, and the light is on for approx. one minute, then it goes out.

When the CEL is on, the engine feels slightly hesitant or 'pulsing' - at all other times it is fine.

I'm imagining it is a sensor (the car has done 94k miles, FSH from new), so before I give it to Subaru, what are the likely candidates please?

I've done a JECS ecu 'reset', and no fault codes are showing (CEL pulsing at 1/2 second intervals).

Thanks.

ReggieMY99

If the CEL is not showing there wont be any error codes

do the diagnostic from cold when you know the CEL is on

could be a knackered knock sensor playing up, this should show up on diagnostics but only if the CEL is on

orangecurry

Thanks Reggie - I'll try that. I assumed that if there was an error, it would be remembered by the ECU and displayed during diagnostics!

The trouble is the CEL isn't on at start-up, and only lasts a minute when it does appear.... I'll have to be quick

In this case, should I leave the engine running when I connect the greens and blacks?

ReggieMY99

Well it should show up on historic error codes, dont turn on the engine when you diagnose the ecu for codes

orangecurry

Right - driving the car from 'cold' this afternoon, the CEL came on (two minutes into the journey again) and so I quickly pulled over, ignition off, attached the greens&blacks, ignition on, and got 2 long and 2 short pulses.

So nice guess on the Knock sensor, and thanks!

Is it OK to drive with this temporary error (lasts one minute at journey start)?