Immobiliser Issues

And always check that there is actually a chip fitted in the master key as it is removable.
The X9 and all other Piaggio scooters are factory fitted with a built in transponder immobiliser system. The Immobiliser itself is built in to the ECU on fuel injected bikes and uses a decoder to read and store up to 5 ID transponder codes embedded in keys plus the original master key chip code. Once the master key code is used, it is permanently embedded into the ECU for life so you cannot use a second hand ECU without itís matching master key and decoder as a set.

26082011010 (WinCE)

NOTE - the 250 Honda powered X9 (98-04) does not have an immobiliser system.

The most common problems X9ís suffer from with the decoder is the failure to read the key transponder and therefore not disabling the immobiliser. The usual cause of this is a failing detector antennae which fits around the ignition switch and connects to the decoder.
On carburettor induction models there is no separate decoder, it is built into the CDi unit. Similar general rules regarding master keys and programming service keys apply but the expense of replacing all the components is not that great as on a FI model.
Replacing the antennae is a simple fix. Occasionally the decoders fail and replacement is the only fix, but you cannot use a second hand unit which has already been used with a different master key, it must be a brand new Ďvirginí unit.
Once replaced you need to use a master key to unlock the system or it will be limited to 2000rpm so if you donít have a master key you are in trouble hence the warning about not having the master key. The only option then is to replace the ECU, decoder (or CDi) plus ignition barrel and all the keys to gain a master key which costs several hundred pounds at least!
If you simply need new locks and keys, then if you have a master key, all you do is swap the transponder chip from your old master key to the new one and program the new service keys into the system. Programming is done by a simple timed key swap sequence you can do yourself.
If you donít have a master key you need to replace keys, locks, decoder and ECU at a cost of several hundreds of pounds! On a non injected bike you need keys, locks, and CDi.