try changing the sensor? i've read something about this on the R53 owners club group on facebook today and would you believe I can't bloody find the discussion now!

 

Sensors probably fucked, I've been through about five in my minis lifetime.

 

Yeah it may be that too. But the fact that it reads the temp correctly sometimes (for about 2-3sec) then go crazy again, going from -40° to real temp then to 50° degree.
That made me think that it may be the connection, I'll check that on the week end, and if I can't find something disconnected/badly connected, then yeah, the sensor will be fucked

 

maybe the connector or the wire chafed on the bumper carrier? If the bumper has had to come off these can get yanked. They do read 40 when disconnected iirc

 

I found what's wrong...I lost everything but the wires...What do I do now ? any Idea where I can find all the pieces missing ?

 

https://www.realoem.com/bmw/enUS/sh...enUS/showparts?id=RE32-EUR-07-2004-R53-Mini-Cooper_S&diagId=65_0745#65816936953

a breaker is probably the easiest. I'd get the sensor and connecter cut off with some wire tails and then solder it onto your bare wires

 

would this Ebay one do the job ?

 

Yep looks like it

Is the bracket still on the back of the bumper? It might be moulded in though

 

There is no bracket on the JCW bumper, you have to ziptie it to a hole at the same location

 

^ what he said, should do the job, I had to re-solder one on my other car and it was fine.