I have an X reg Polo estate, 1.4 16v (75bhp) APE engine.

Recently I had a problem where the car would start but then cut out. The immobiliser kept kicking in and stopping the car from running.

I plugged into the OBD2 port with 3 different diagnostic machines but the ECU would not communicate with the diagnostic machines (engine off, ignition on).

I ended up taking it to a friend who plugged in while the engine was running (i didn't want to turn the engine off incase it wouldn't start again) and the diagnostic machine did communicate with the ECU and told me what my faults were but he didn't want to delete the codes while the engine was running.

Could this mean that my ECU is on its way out?

Also my camshaft sensor is doing nothing. When I unplug it while the engine is running it doesn't even flinch.

I tested the connector with testing lamps and there is a live connection across the terminals. I tried replacing the cam sensor but it's not changed at all.

Any help would be appreciated.

Edited 12 September, 201511 yr by Sil6ky

Not all scanners can work with vag cars as it uses a different "language" as more main stream vehicles.

If you got someone with a high end scanner it will work with no issues. The engine doesn't have to be running but ignition does have to be on.

Also, if you have a look on eBay or Amazon for vagcom - this is a pc based diagnostic scanner for vag cars these are cheap and very handy to have and works perfectly with your car and will tell you what the error codes mean. It's sometimes a little tricky to install but if you follow the instructions exactly it should be simple.

Cam sensor should make the engine cut out when unplugged. It's possible that the ecp has detected a fault and stopped sensing from it and revert to its stored values. I have heard of this for other not as important sensors but not for a cam sensor.

Have you tried unplugging it and revving the engine? I'm sure it would bog down and cut out.