Hi, I have an Audi A4 B6...2003 Quattro TDI 2.5.

Ever since having it we've been having problems with the remote central locking, sometimes it works and sometimes it don't. Sometimes it will only lock and sometimes it will lock and unlock...others it won't do anything.

We started to get a new problem where you would start the car and it would turn off, the car light with the spanner is flashing to say the immobiliser is engaged. Normally we turn it off and try again and this works, well this problem disappeared for a while.

Tonight it came back with a little vengeance, this time the usual trick of turning it off would not work at all no matter how many times we tried. I called for the Mrs to bring the spare key, she claimed when she used this before she wasn't having a problem...the spare key does not have a keyfob. We tried the spare key and it did not work tonight.

The Mrs was having a mess around and eventually the hazard lights started flashing really fast like the alarm was going to go off. We couldn't stop it from doing this...and also whilst playing the remote central locking totally stopped working.

Eventually I was just messing around wondering how I'm gonna get my car home, I pulled the fuses one by one to reset stuff until I got to fuse 15...the display cluster and the hazards stopped flashing. I put the fuse back in and the keyfob started working, then hey presto the car started no problem! So it seems that a reboot of the cluster has kicked the immobiliser back into touch and we got home safely.

So now I'm wondering what the hell is up with this, I've read quite a few threads talk about replacing the battery in the keyfob. I've done this and we even had a dealer try a different key, which seemed to do the same thing...well this is what the Mrs said anyhow, she took it in not me.

I guess no mechanical parts are faulty if an electrical reboot of the system causes it to spring into life? Where is the actual electrical side of the immobiliser stored, is it part of the ECU/CCM or the cluster?

I'm just tracking down someone who has VCDS in Redditch to run a scan for any faults...but any ideas would be really appreciated.

 

the immo is in the cluster. the actual immo chip in the key is not powered by a battery. the chip is energized at a certain frequency when it enters the field near the ignition.

you may have to call the dealer and have them order a new key and program it to the car.

 

Yah, but there in lies the problem...the car hasn't totally lost the sync to the key because after pulling the fuse out on the instrument cluster (fuse 15) and putting it back in again, everything sprung into life.

The remote central locking had stopped working again, and I used the old stick the spare in the ignition whilst locking the door / pressing the keyfob to get it working again.


So the situation I'm in now is the remote central locking is working and the car is starting up without an immobiliser problem. The problem of course is these are intermittent problems that will come back again, and last night was the worst ever when I couldn't start the car no matter how many times I tried...and the final fix was to remove and reinsert the fuse for the instrument cluster and bam...we're off again.

The questions I have, I guess, is what can cause this intermittent problem of the remote central locking not working and the car not recognising the key first time? Does it sound like a faulty instrument cluster, seeing as "rebooting" that seems to have fixed all...but then I guess when you take away the power from the cluster you're also taking away power to other external modules.

Hoping to have someone do a VCDS scan this weekend and maybe see some groans...but if anyone has any ideas please bring them along.

 

And yeah, to reiterate...last night neither my main key or my spare key were being recognised by the immobiliser, it was having none of it until I had pulled and reinserted the fuse.