07 plate golf 1.9 TDI

[106rallye]

Has anyone had an issue where the car won't start and in position 3 of the key turn the main engine fan turns on? Car will just crank but if you apply some throttle It will try and fire! No engine management light on it won't connect to a reader either. Very confusing?

[Crasher]

As I said in your PM and with the extra info of no ECU comms, that suggests failure of the engine ECU relay.

[mickeybo]

engine code would be helpful

[Robert Powell]

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The fan kicking on with key position 3 could be a temp sensor that's gone wonky or stuck, making the ECU think the engine's overheating when it's not. The fact that it won't talk to a diagnostic reader is a big red flag - check your OBD port and fuses first, but it could also mean the ECU itself has taken a hit. Since it'll try to fire with some throttle, I'd be looking at fuel delivery issues too - maybe a weak fuel pump or clogged filter starving it of juice. Could also be a dodgy crank position sensor giving mixed signals to the computer. I'd start with checking all your fuses, especially the ECU ones, then move on to testing fuel pressure if you can. Definitely get that diagnostic connection sorted first though, as that'll save you hours of guesswork