Engine will not start 2.0 sport MK3 2008 - Help!

Technical Area Electrics & ICE
2

Hi All, last week when it was cold and snowy, on Sunday evening I moved my car from its sheltered position onto the road so I would not get stuck in the morning.

Without thinking about this I had put my car in an exposed condition.

On Monday morning the car would not start, just the a clicking noise. The battery was in good condition.

In the evening the AA attended and actuated the starter motor relay, the starter motor turned but the engine would not start.

I tested the relay and it is now operating okay, after leaving it in the house to warm up, I have one on order as a precaution.

I tested the ignition key circuit to the relay and this worked but the earth had no feed, I made up an earth feed from the battery and now the starter motor turns from the ignition key.

But the engine still will not start and cannot communicate with my OBD 2 meter.

I have checked all the fuses and all are okay, both under the bonnet and by the passenger foot well.

Any advise would be most welcome. 

Thanks

Derek

3

I’m not familiar with the MK3 setup as the electronics, like all modern cars, became so much more complex, but the fact you can’t communicate with the ECU via the OBDII socket seems bad news. Do all the dashboard warning lights come on as normal when the ignition is first turned on? If they do I would have thought you should be able to interrogate the ECU via the OBDII port. Can you borrow another reader just in case yours is playing up. If it wasn’t for the lack of OBD communication I would have suspected the immobiliser system but maybe they are intrigal on the MK3.
D

kinda dum after thought, have you tried disconnecting the battery and waiting a few minutes to reset the ECU? Could be worth a try.

4

Thanks for the reply, I have tried the battery disconnection trick but this did not work, good idea about the OBDII reader will borrow one tomorrow.

Cheers

Derek

5

Check to see if you have battery voltage at pin 16 of the obd socket. Also,does the engine Mil light illuminate with ignition on?

6

Seems like an earthing fault to me somewhere. Has the scuttle grommet been sealed to stop water ingress.

7

Does the immobilizer light go out? Try using the other key