I just bought a focus 1.6 tdci and serviced it, started it up and it fired up 1st turn of the key and ran for 2 - 3 minutes then died

i then attempted to start the car and it just turned over , i checked the fault codes and u1900 (Can Bus Fault) was stored, as well as another one for the instrument cluster which pretty much said that the car was immobilised and another code relating to insufficient security data

i reset the codes and attempted the start the car to no avail, i then attempted to jump start it and it just turned over, i checked the battery and the positive terminal has been arcing so i fixed it

the speedo then started displaying ------ and now it wont even turn over

i then charged the battery overnight and checked all the fuses (3 amp in engine bay etc)

tried again today and the immobilizer flashes 16 times (Can Bus Fault)

Before the car died autocom could connect to all the ecu's/systems on this car but now the main ecu wont respond, anyone had this issue?

anyone got any ideas how to start this car?

I had the same fault code as you, regarding the immobliser. I have a 2.0tdci c max so not sure if you have the same fuse box in the engine bay lift of the fuse box cover and you may have a large blue multi plug. Make sure this is firmly in clicked in to place, I then disconnected the battery for an hour. Apparently this resets the systems on the vehicle. This worked for me

Basically there is a shortage in the wiring not being able to communicate to the cluster which stores the immobliser.

It sounds to me like you have an air lock in the fuel system, or the fuel filter wasnt topped up fully. I recon you have flattened the battery as you were priming the fuel filter.

I see a new battery in your future once you have gotten the car running properly again,

Sounds to me like an ecu or wiring problem. If the engine was turning over then the battery wasn't your problem.

Turns out that the junction box in the engine bay was at fault, i couldn't get a feed from the main fuses in the junction box so i checked the plug going into the junction box and found that alot of the pins were bent so i straightened them, then the terminals on the junction box side were spread too far apart so i tightened them all

reconnected the battery and been great ever since

Fantastic result and another note to add to the memory bank :-D

Thanks for coming back to advise of the fix. Always helpful!