Hi. My 2013 Diesel B Max is great but I have an intermittent problem with all heated screens and mirrors. One day they will work the next day not and so on. Any one with any ideas.

The B Max is clever (or stupid to some) in that when the battery charge level is low, the management system renders some heavy use features inoperative.
My B Max did need regular daytime use to keep the charge up.
Try an overnight trickle charge.

Hi. Thanks I have tried that but the battery test perfect and is fully charged.

I had this problem before I changed my battery for a new one (7 years old) Took an half an hour to extract it and similar time to put it all back.

Hi Thanks that's my next try.

I just happened to have a battery I bought for another car and took it off before I sold that car.
This battery was the same size but was a bit taller, The original B-Max battery has this large plate over the top of it to hold it in and other metal straps, I Did Not fit back this large plate and it is still very secure with the other straps.
As you can not get at the Negative terminal I very carefully removed the positive terminal first (Not good practice as there is a risk of shorting it to earth (the cars body).

You have to remove the Engine air intake cover ( you can leave the filter in place but protect any dirt etc. dropping onto it.) then remove all the battery straps and the plastic front of the battery box.

You can only get the battery out by angling it at about 45 degree's.