this ones problably been done before but me p38 has an alarm fault nothing comes up on diagnostics it locks,imobilises, dead locks been told that it may be ultrasonic sensor in car up by passengers head any thoughts?

Not much to say really, it probably is the ultrasonic sensor, seems to be the case in every alarm fault thread ive seen. Its simple to remove, just pull on it and it will unclip from the roof, unplug and replace.

-Wills

Usual tell tale sign that the ultra sonic sensor has gone is that "Alarm Fault" will flash briefly when the key is inserted in the ignition switch. As Wills said it's usually the problem- can you do a substitution with someone else just to check??

Just changed my sensor still got alarm fault showing but at least thats one thing elminated

Check the pins at the ultrasonic sensor - I had one where I swapped the sensor, and still had the fault.

Looked closer at the pins, and one of them had corrosion on it, rather badly to the point where the wire pretty much came off in my hand.
I wired another pin in and that sorted it in that case.

I've also heard that if the key in ignition switch is intermittent or it thinks the key is always in the ignition, then that can cause an issue too - but it is far more common to be related to the ultrasonic sensor. If the little door doesn't come across the ignition barrel when the key is removed, then the barrel can be cleaned out with something like MAF or brake cleaner (something that doesn't leave a residue - don't use WD40 as it will allow dust etc to gum up) and then lubricate the lock barrel with some graphite powder.

Ok marty thanks for that will have look at that cheers mate

Hi marty tried wires and maf lube still same back to drawin board thanks though mate