I’ve replaced the drivers door handle on my P38 with a brand new factory one. I got the complete set including ignition barrel, door handle, 2 FOB keys, a glovebox latch and a valet key.
All work fine BUT .......
I cannot get the key to sync the central locking.
Whilst there are numerous “this is how you sync the key” methods on the net, I am actually blue in the my face from trying.
I know it’s the techniques I’ve been using because I recently changed the battery in another P38 and I can’t get the central locking to work off the FOB.
So.... does anyone have a “tried it a hundred times and I guarantee it works” method to get the key to synce central locking remotely?

Just deleted your duplicate post so you don't end up with 2 threads running with answers in both but I'm 99% sure it won't work. The keys are coded to the BeCM and unless you were supplied with keys with the same code to match your vehicle, they aren't going to sync. If you have the data sheet for your car it will have a number for the lockset barcode stated on it. Over on the dark other side they reckon that there are no more NAS keys available so it seems highly likely you've been supplied with fobs that aren't coded to your car but are just random fobs. You may even have been supplied with 433 MHz rest of world fobs rather than 315 MHz NAS ones, in which case the receiver would need to be changed for a 433 MHz one as well. To get them to sync you need to find out what code is in the keys and then program that into your BeCM. However in order to do that, the BeCM needs to be unlocked. At the factory they were programmed and then locked so critical settings couldn't be changed by someone poking around with a Nanocom or similar. To unlock them, you need Marty who has the kit to read the code from a key, unlock a BeCM and program the same code into it.

Which, I have to say, is a miraculous level of support for a 20 year old vehicle. Hats off to the kiwi chap (and his tree hanging buddy).

As stated above... If you bought a complete lockset, then the fob code being transmitted by your new fobs will be different to what is programmed into the BECM.

Albeit in the UK, but info have the capability of reading the code the fob transmits directly and then being able to reprogram that code into the BECM to then allow those fobs to work and the remote to sync properly with the BECM.

If you're interested in me taking a look, I am happy to, but would need one of the key fobs and the BECM logic board sent to me, so I can hook it all up and sort it out.

There it unfortunately isn't any other way of reprogramming the code in the BECM, even if you do have the lockset code from LR for the new lockset.

Feel free to drop me a PM or email if you want to discuss more!

Gilbertd, I was able to order not one, but two complete lock sets for my vehicles. I went to buy one at the dealerships and when the guy behind counter said “yes we can get it” I bagged two. I did have to supply my original Vehicle titles for both P38s, my drivers license and a lot of cash, but I justified the $$ by the rarity of the vehicles and the perceived difficulty in getting a full set. Both sets of locks were cut based on my vehicles VIN numbers.
If people want to get these lock sets send me a message and I will forward you the dealerships address. Bear in mind, however, that you have to go there in person....
I called the dealership last pm and they advised that they could program the key to the vehicle if I brought it in.... bad news is that there is a waiting time of 3 weeks to get in there. Apparently, according to the service manager, they should have offered to program the key to vehicle when I bought the set...
Let’s see how that goes.
Onto the main subject, can anyone tell me a fool proof 100% certain way to get my FOB to work on the central locking..... this is for the vehicle I removed the battery from for a while and now the remote fob won’t work in opening and locking doors.....

You can swap the key blades across fobs to keep your original transmitter.

original fob looked like the dog chewed it.
I’ve tried pressing the lock button, waiting for light to flas quicker, turn key to lock, hold and return to middle position. The. Press open button until light flashes faster, turn key to open position, pause then back to center position and all combinations there of yet the bloody thing won’t sync for central locking. That’s after replacing batteries in FOB. This FOB is the original one and worked fine prior to changing its batteries.
My RR worship manual is in lockup as we are moving house and I’m at a loss....
Surely there is a proven method to doing this...

You turn the key in the lock and then press the button on the fob until it flashes faster, release the fob button, then return the key to centre. Then repeat the other way. Sometimes, it won't sync if passive immobilisation is turned off, so you could try turning it back on, doing the sync, then turning it back on.

However, in saying that, one car I look after lost sync after the battery went flat and flatly refuses to re-sync. Passive immobilisation on or off it still won't sync. I've no idea why as it used to work fine and the owner just uses the key in the lock. Unfortunately she only has one working fob as the other one was lost and found after spending 10 months laying outside in the garden so is in a bit of a sorry state, prior to that both worked fine.

Passive immobilisation..... how do I turn it on and off?

With Nanocom or similar. In BeCM, Settings, Alarm.

On it. In process of moving house so everything related to vehicles are in storage for the foreseeable future...

Change your fob batteries first! :)

Oh, and it's a P38, there's no 100% sure!