Immobiliser Problem

[scos]

Hi guys,
I have a problem with my 16V Cupra immobiliser and wonder if anyone can help. It will randomly turn over and fire but then the immobiliser kicks in and stops the engine. It's been happening on and off for a few months but seems to have gotten worse recently so I am gonna have to get to the root cause.
I did some research a few weeks ago and acquired the VAGcom software and interface but all it told me was that the immobilser had blocked the engine start (fault code 17978). It also said to resychronise the key fob, which I did and the problem went away for a couple of weeks but now its back and resychronising doesn't cure it any more.
Has anyone had a similar problem or know what else I should check?
Many thanks,
Scott

 

[Fl@pper]

i don't know about check as such but have heard of the chips being dodgy - try it with a spare or another key but also the reader coil that is wrapped over the end of the steering lock is worth a look

its the bit that reads the chip and sends a signal to the immob. ecu

 

[scos]

Great thanks, will check that out tomorrow. Now that I think about it someone did mention something about a part to check on the steering column when it started playing up. Will let you know how it goes.
Cheers.

 

[Fl@pper]

worth trying another key - or at least getting your only one cloned

would eradicate one part of the equation

 

[scos]

Tried to plug my VAGcom in today but some problems with my laptop so wasn't able to check the fault codes again. Did have a look at the steering column but couldn't see anything wrong so just unplugged and reconnected a couple of things to make sure there were no open circuits. Also had a look at the relays and checked they were all pushed in properly, one of them appeared to not be fully down and after that it started okay again so maybe that was it??
I guess I won't be sure until a few weeks have passed without a recurrence of the problem. Incidentally I think I recall one of the relays also being slightly warm - is that normal or could it suggest a problem? I don't have a haynes manual indicating which relay does what so not sure if it was related to the immobiliser - will have to look it up.
Anyway, thanks for your input