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Hi I'm new to this forum + any forum so I apologise if I've posted this in the wrong place or if this has already been discussed however I can't find my issue anywhere on the internet!

Basically I bought my girlfriend a 2001 1.8l turbo 120,000 miles on the clock.

To start with the drivers door had a separate key to the other passenger door/boot/ignition which I probably should of thought more about when I bought it! The first problem was that you could only open the drivers door and turn the engine on to then unlock the passenger door or else the alarm would go off, which we could live with.

After a couple of months the immobiliser symbol came up on the dash and all of a sudden whenever you put the key in the ignition it would set the alarm off.

After slamming my head against a wall for a bit I realised it could be the door module not sensing that the door has been opened hence the car thinking someone is trying to steal the car so I replaced the drivers door module which kind of fixed the issue.

The immobiliser symbol went off and the alarms were still going off but putting the key in the ignition would turn it off, and I also realised that by turning it in the ignition would actually deactivate the alarm system (red flashing light by drivers lock turned off) and just via using the lock and unlock button on the inside of the door it would never activate the alarm (the flashing light would never come back on because the alarm is still deactivated)

Also at this point I swapped the driver side and passenger lock so really only one key was needed.

This worked absolutely fine before I started to fiddle with stuff!
Basically the key that came with it was in bad condition and didnt have a key ring loop so I bought another case for £5 off eBay and went about putting the blade/circuit board/transmitter into the new case but accidentally smashed the transmitter.

Since using the new key it turned the engine on but after a day the immobiliser light came back on so stupidly I thought to lock it from the outside (activating alarm + Turning on flashing red light) and now because the car doesn't recognise the key (I think) I can't get it back into that state of calm where the alarm was deactivated and now even if I open a door the alarm will go off. Weirdly I can still start the engine.

Sorry this is really long and I've tried to explain it best I can but I'm out of ideas now, on paper I guess I just need a new key but surely if the car doesn't recognise the key then it wouldn't turn on?

Thanks anyone that has read this far I appreciate any help! :):)

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From what i can tell, you are dealing with a immobilizer issue and possibly another fault that is kicking on the alarm. I wonder, if all the key fobs you are using; are correctly coded to the car. If the rfid chip is bad, you would need a new one and have it coded/matched to the car. It could be, something is working intermittently; thus, the goofy problems.

Each key fob has a small rfid chip/capsule; that is matched to the ecu. As you put the key info the ignition; the reader coil, talks to the rfid chip and gives, the "ok" for the car's ecu start (activating the ignition). I wonder if you transferred this rfid chip; to your new replacement key fob case?

Here is a great faq; that explains how the immobilizer and the wireless key fob work:

Having a vw specific scan tool; would help, figure out, what trouble codes are being thrown from the immo or possible faults from the comfort control module. This can bring some sanity to your troubleshooting process and narrow down the problem.
A new vw scan tool has come out; called Obdeleven which is $60 USD and it runs on android devices. Other scan tools that can do programming; are the VAG 401, Foxwell NT500 or the Ross Tech VCDS.

Actual programming; can require a program like Vagtacho and then another to do the coding. Depending on your ability and willingness; to get all the tools needed, it would be leas hassle ti have a auto locksmith or a vw dealer do the work. Let us know; how you want to proceed and we can go from there. Thanks! :)

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