car wont start, tried nearly everything

Hi, this is my first post on the forums and I'm in need of some help.

Let me start by going into a bit of back ground on the car.
I have a 2004 e53, 4.4i sport, lpg converted with 80k miles on the clock.
It has been well looked after with full dealer service history.

After buying the car, it started and ran lovely for the first 4 days.
Then out of nowhere it wouldnt start, just click click click from under the bonnet.

So after doing a bit of research, I changed the battery. That didn't help.
Then changed the starter motor, that didn't help either.
Then replaced the ignition switch, no change.

I've tried both keys, neither make a difference, just click click click.

The car started at random times, but now I'm completely lost as to what it could be.

Does anybody have any suggestions?

Thanks

After you changed the battery, did you have the battery registered? We had that same issue. The computer has to be set to recognize the new battery.

I was told its only 2007 and up that needed to be registered.

Thanks

No. My X5 2003 wouldn't start until we registered the new battery so that isn't correct.

Ill look into that, thanks

Just to keep everyone updated.

After looking into various other causes, it turned out to be a faulty DME.

The car is now back up and running.