Breezy_Pete

Secondhand genuine from ebay. Photo of perceived problem?

Measure either side of the fuse that connects alternator to battery. First one of the strip fuses above battery, usually.

Fling your VIN my way and I can tell you which rad part number you have.

Hope the mating connector in the loom is OK?

@mczakk PM incoming in a minute.

I'm seeing signs of availability (on partslink24) on kits suited to Roomies built on or after 28/05/2012, is the one you're looking at a 12-reg or 62? If the latter there's a decent chance it was built after that date. Sorry, but cross-checking those part numbers against what's on offer at LLL parts suggests they're gone too. ☹️ Have you @Rheumy got an image of the connector involved? May well be able to still buy that?

Hmm, how many connectors, pins, wires...?

It will have the combined unit; I think March 2010 saw the last of the separate central convenience control units in Roomsters. @Tech1e almost certainly knows the answers to your other queries. If you message me the VIN I could look up which BCM part number it has, if that's any help.

Mild pride dentage I think, only, ta.

Following a bit of an off-road-edge incident, reports from partner of symptoms that sound a bit wheel-balancey...

Need to know engine code as well if you would like me to try to look up wiring info. A quick glance at a guessed CUNA engine circuit suggests there are two oxygen sensors, which surprised me, and possibly the garage that may have replaced the wrong one?

@mczakk were you able to navigate the parts catalogue link I supplied?

Follow the hard plastic pipe from the brake servo (behind brake fluid tank) towards the engine. At each point where it connects to the one-way valve, look and feel with finger tips all around it for cracks. If there is another connection of hard pipe nearer the engine, check there also.

Manual or automatic gearbox?

Can be because of a brake servo vacuum hose that has developed cracks and is leaking air. Which engine size does your car have?