If you want to use the genuine Audi flip key type remote, check the part number on your central locking pump (located in the boot wall)
It should be a twin outlet 8L0 type pump.
If the suffix letter is higher than 'A' (8L0862257 'G' for example) you have the RF receiver in the pump, and can use a flip key.
If you have an 8L0862257 'A' pump, you will have to swap it for a higher suffix version.
Then purchase the correct remote for your car, and sync it to the car.
If your car only came with central locking on the key (no remote locking) you will have to use vag-com or similar to activate 'Keyless entry' in you central locking module.
If you have an immobiliser, you can get the 'static code' capsule in one of your main keys cloned, or sabotage an old master key and swap the immob capsule (key end of remote)
The Audi system has poor range, and it is more economical to purchase one of the flip key 'keyless entry' kits from ebay.
They generally have far superior range than the OEM remote, give full closure and activate the alarm.
I retro-fitted the Audi flip key 'remote locking' system into my 97 A4, but am now using an aftermarket remote system.
