Jag ownership has a habit of sending me on wild goose chases (vacuum leak being a classic) but this one has really annoyed me! So I purchased the car late February last year, noticed the rear sensors (no fronts on mine) worked only when they felt like working. Spring came and they worked fine throughout the summer and into autumn (southern Spain warm climate most of the year) only to start failing again and not work at all in winter. Reading up I see others with the same issue and even some replacing the whole thing for a generic system. Not me, I want only OE, so jobs done to figure this out:

• Checked the sensors and one was not giving that clicking sensation when passing a finger over it, with all the others clicking away happily. So I replaced that one with new but nothing. Didn't think to check the others again, just thought this wasn't the issue. Could it be a wiring issue?
• Goose chase part 1: Picked up a used harness from the UK but no change. Could it be the module?
• Goose chase part 2: Opened up the module and checked for obvious signs of wear replacing the two large capacitors on the PCB as it was the only thing I could think of that can fail in cold temperatures especially if worn out. Nothing, nada, zip! But I have a renewed module now I guess...
• Finally noticed none of the sensors worked..... So picked up 4 new sensors on UK fleebay (for Land Rover it said but ref was the same) at minimum cost. Tested them in the summer heat and with the second loom just to make sure everything worked and now with cooler climate failure, tested again with the spare loom, all good, so replaced the sensors and hey presto, fully functional system again!

Could have saved myself so much hassle had I checked the others when I replaced the first sensor but got there in the end and no more old school parking. I now have a spare wiring loom (tested) and a spare unused sensor if anyone's interested...

 

Capacitors replaced on the module PCB: