Immobiliser problem?

[The_Laird]

I've been doing a lot of short runs recently, with no starting problems, but today the car started and then cut out. It did the same 3 or 4 times and the immobiliser light (I think that's what it is - the car with a key symbol) came on.

I swapped keys and all seemed fine.

Any ideas folks? I don't have time to run a scan as I'm up to my ears in packing!

[steamship]

Can't offer any suggestions, but it happened to me about a year ago. Was sitting in a side street with a few other cars waiting for someone to complete their parking shenanigans when the car just died. I tried it about 5-6 times before it worked again, and it was one of the new Bentley style keys I bought during the North Wales annual meet. Scanned the car afterwards, but it didn't show up any errors at all related to it.

[MikkiJayne]

Try giving the steering column cowling a bit of a knock from underneath when it does it again. Not too hard- just enough to get it's attention. I see this quite a bit on this generation of Audis (B5, C5 and D2) and its usually the connector to the immobiliser reader coil on the ignition barrel. A bit of percussive maintenance is just enough to make the connection again so the ECU can read the key.

The longer term fix is to dismantle the cowling to get to the connector and then just disconnect & reconnect it a few times, then give it a tiny squirt of WD40.

The contacts are very small in this connector and not very well supported. I think they just become a little loose & dirty with age.

[briang9]

Like I said to you earlier if the other key works it could be the battery in the key, or the key has got out of sync somehow, try new battery first.. or I think this applies across the Audi model range..

http://www.ebay.co.uk/gds/How-To-Pro...0293524/g.html

unlikely I guess given your spare key works but this thread from Ranj describes what happens if the wire is suspect..

http://forum.a8parts.co.uk/showthrea...ht=immobiliser

now get back to packing

[RS6]

mine was doing the same thing a few months ago the car would start and then cut out straight away, the immobiliser light would flash each time, started happening just once a month on the driveway then became more frequent, wouldn't start at work one evening with out jiggling the key each time and being very patient.

There is solution to this is to swap the cable out, inside the steering column cowling you can change the immobiliser wire, if you have VAGCOM it should show as a fault for Key Signal in the ECU

Locate the wire/cable, something like £11 new from audi, if you google it you can track down a guide and part number (sorry don't have it to hand ) this can then be swapped over with the old one, giving you perfect signal and new contacts again each time you start the car

its just wear and tear but very annoying

[RS6]

i've found the info

Immobilizer wire part number 8D0 972 275.

and guide hope it helps

http://www.audipages.com/Tech_Articl...rereplace.html

[27litres]

Originally Posted by briang9

Like I said to you earlier if the other key works it could be the battery in the key, or the key has got out of sync somehow, try new battery first-

Immobiliser transponders in all Audi's of this era are energised by the reader coil.
The battery only powers the remote entry which has nothing to do with the immobiliser. The remote entry can go out of sync occasionally and the batteries can go flat, but this doesn't happen to the transponder.

My understanding of how the immobiliser system works is that the immobiliser will interrogate the key on start up and if it gets the correct response or recognition it allows the engine to keep running. It only does this at startup and its job is then complete until next startup. The whole time the engine remains running the immobiliser is inactive, only becoming active again once the engine shuts down.
Quite how Steamship had his engine stall in traffic when already running I don't know.

Any immobiliser issues will be down to the reader coil and any associated wiring (and on prefacelift models the immobiliser box - facelift models have it incorporated in the dash module).

In my experience, immobiliser action resulting in start/stall happens occasionally but infrequently. I would only look for a fault if it happens frequently or causes problems.

[MikkiJayne]

Originally Posted by 27litres

Immobiliser transponders in all Audi's of this era are energised by the reader coil.
The battery only powers the remote entry which has nothing to do with the immobiliser.

My understanding of how the immobiliser system works is that the immobiliser will interrogate the key on start up and if it gets the correct response or recognition it allows the engine to keep running. It only does this at startup and its job is then complete until next startup. The whole time the engine remains running the immobiliser is inactive, only becoming active again once the engine shuts down.

Exactly that

The replacement immobiliser wire only applies to prefacelift cars with the separate immobiliser ECU (white box under the dash). Facelift cars have the immobiliser built in to the cluster and the reader coil connection is part of the main harness so can't (easily) be changed separately. That said, you could buy the prefacelift wire and splice it in to the main harness to get a new connector. Taking it apart and putting it back together usually solves it though.