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engine wont restart when warm ?? sensor fault?

Posted: Mon Apr 14, 2008 9:01 am
by JJmac
Pulled into a service station for fuel and the car wouldnt restart - so i left it for 20 mins then it fired up first time - this is third time this happened recently - anyone else have similar problms?
Im thinking it must be a temperaturer sensor fault making the computer think the engine is too hot , so kills the ignition until it cools down to about 70 degrees. Coolant levels are OK.

If so - how much is a sensor ? and is it difficult to replace?

cheers.

RE: engine wont restart when warm ?? sensor fault?

Posted: Mon Apr 14, 2008 9:11 am
by SimonS4MTM
Does it run and then cut out, do your dash lights and DIS come on as expected?

RE: engine wont restart when warm ?? sensor fault?

Posted: Mon Apr 14, 2008 9:24 am
by JJmac
Dash lights and displays come on as normal and no faults are displayed.
Its only when i turn the engine off after is been running for a while and then try to restart it sometimes wont fire up until it has cooled down. The engine hasnt cut out as a result of the fault .

RE: engine wont restart when warm ?? sensor fault?

Posted: Mon Apr 14, 2008 10:13 am
by GardinerG
Does the engine turn over? if not then the only time I have seen a similar fault is when the starter motor is shot or it's heat shield is missing (gets too hot from the running engine). Had this on a Golf and seen it on a 209. Dunno if that is your problem, but the engine won't turn over at all if this is the case.

RE: engine wont restart when warm ?? sensor fault?

Posted: Mon Apr 14, 2008 10:56 am
by JJmac
The engine turns over ok - it just doesnt fire up - thats why i thought it was a electrical fault stopping fuel flow to the engine until it cooled down again.

RE: engine wont restart when warm ?? sensor fault?

Posted: Mon Apr 14, 2008 11:13 am
by GardinerG
Do you know anyone who can do a fault scan using VAG-COM or similar? Might help.

RE: engine wont restart when warm ?? sensor fault?

Posted: Mon Apr 14, 2008 11:20 am
by JJmac
think i will have to take it to the local garage and let them have a go at it.
I warped the discs driving across germany a few weeks ago and i have been told that its not a good idea to have stock discs skimmed. anyone know of a good place to buy from?

Re: engine wont restart when warm ?? sensor fault?

Posted: Tue Apr 22, 2008 1:01 am
by UKS4APR1
JJmac wrote:Pulled into a service station for fuel and the car wouldnt restart - so i left it for 20 mins then it fired up first time - this is third time this happened recently - anyone else have similar problms?
Im thinking it must be a temperaturer sensor fault making the computer think the engine is too hot , so kills the ignition until it cools down to about 70 degrees. Coolant levels are OK.

If so - how much is a sensor ? and is it difficult to replace?

cheers.
Hope you got this sorted, if not it's probably the coolant temp sensor - it's a common problem and there is an improved (green coloured) version to replace it. Easy to do, ECU thinks engine is cold and overfuels. It's a 4-pin sensor, the other 2 pins are for the temp gauge on the dash.
Get it here....... https://sslrelay.com/s74326199.oneandon ... 9501A%3D29

RE: Re: engine wont restart when warm ?? sensor fault?

Posted: Thu Apr 24, 2008 5:06 pm
by jb7_uk
had exactly the same thing on my old W-reg (facelift) A4 2.8Q.. as above.. new sensor sorted it right out.

RE: Re: engine wont restart when warm ?? sensor fault?

Posted: Tue Apr 29, 2008 6:22 pm
by JJmac
I finally got round to replacing the temp sensor but the fault was still there. Had it checked out on the computer and a crank shaft sensor was throwing up a fault. Has anyone had problems with crankshaft sensors ?? , the engine starts fine when its cold and when its at full running temp(90) but when i leave it off for 10 mins after its had a long run it doesnt want to start - Does this sound like the crankshaft sensor is about to die? is it difficult to replace?

cheers.

RE: Re: engine wont restart when warm ?? sensor fault?

Posted: Tue Apr 29, 2008 8:08 pm
by Harper--D
Had similar problem on the S2, hall sender was knackered. Quick fix was to chuck water on the sensor and it started fine!!! Got sensor replaced in the end!