OK, full story. Had car 3 years – only issue has been coolant temp sensor needed replacement. Other than that it’s always started well – been a good runner.

Heard a rumbling noise in engine bay for few days particularly at low revs, and turning with large steering wheel displacement - forum searches indicated maybe an alternator freewheel pulley issue. Went to wreckers to see similar car from same year – noticed the pulley was a single solid item so just purchased new serpentine belt and tensioner.

Tried to start car to move into garage – wouldn’t start. Bit of vapour emitted from front under the hood when cranked for 10-15 seconds.

Opened up hood and noticed a lot (more than a bucket) of water surrounding battery – drain holes were plugged. Unplugged the holes.

Put front into service position and fitted serpentine belt and tensioner.

Engine wouldn’t start - cranks but doesn’t start – feels a bit rough when cranking as though almost trying to fire on one or two cylinders. RPM on dashboard instrument panel never moves when cranking.

Scanned many times (scanned each time I’ve tried something) now with Ross-Tech vag-com

Various faults have included (they come, I clear them, sometimes they reappear, often not):

Battery voltage too low
Throttle body adjustment not reaching lower stop
Injector open circuit (all 6 injectors – this has only happened once)
Immobiliser immobilising engine.


Currently there's no codes for the engine


Inmobiliser light has come on a few times during cranking attempts– swapped key to other key and issue away. Wait for ages, or recharge battery overnight and immobilser issue goes away.

When cranking, the RPM does increase to 120 RPM on the ross-tech group 1 ( or else 2 or 3 ) – not sure where this is measured from, the crank position sensor or the cam sensors.

Have unscrewed petrol feed at fuel rail and checked - there is fuel at rail.

Unplugged coolant sensor and camshaft position plugs - all plugs seem OK.

Have checked spark plugs – they get wet (implies injectors and pump and ecu working at least sporadically – also implies crank sensor also working I think)

Pulled two spark plugs and cracked while they lie on engine – get yellowish spark so bought new spark plugs.

Opened up ECU box and unplugged it – some corrosion on two corner pins in smaller of two connectors – cleaned off. Rest of interior of box dry – suspect corrosion was there a long time – no wetness or dampness in plastic box. Opened up ECU itself and it looked fine inside – no sign of corrosion or wetness.

Injector common voltage when key on but not cranking is around 4.5 volts – when cranking it goes to about 12v. With voltmeter the grounding line changes implying ECU is grounding injectors (at least sporadically).

Bought new battery and spark plugs

New battery cranks much faster but not starting.

New spark plugs getting wet – covered with blackish oilish stuff – possibly petrol and carbon from cranking. Took all spark plugs out for evening to let accumulated fuel evaporate and reinserted – still not starting.

Took back off plastic manifold to look at back of throttle plate and intake at throttle body – seems good and clean – small amonut of oil from PCV system in black plastic cover – cleaned off.

Removed and cleaned up grounding cable and tested – seems to be 1 ohm resistance.

Would like to unplug lead into coil pack thing (3 items that spark plug leads plug into) on front of engine but can’t figure how to unclip it, to see if it’s receiving 12V.

The varying fault codes imply to me that there's a short somewhere – but spark and fuel into cylinders imply the ECU and sensors are working.

Haven’t checked compression but have no reason to think that’s an issue since it worked then it just wouldn’t start.

Anything obvious that I’m missing? I’m stuck (literally) at this stage, and don't want to be wholesale buying and replacing senors, ecu or wiring loom just yet.

Paul