Why does mex-BT3900U drain my car battery after three days?

[SandyPotter]

I have a Citroen C4 2010 and when the standard radio is fitted no problem. As soon as the mex-BT3900U is fitted the car battery is drained within 3 to 4 days, the same radio was fitted in a 57 plate picasso with no problems what-so-ever. Any possible cures to this problem would be of great help a I like the radio.

[Thalamus. · Accepted solution]

Hi SandyPotter,

welcome to Questions & Answers..

Not sure what the standard radio is but it could just be a coincidence that fitting the MEX-BT3900U causes your battery to to be flat especially at this time of year, have you checked your battery is ok.?

Also it states in theMEX-BT3900U user guide..

So may be worth checking out the Auto off function..