Relay help

[Paul_P]

Hi guys, I need some help with a relay issue.

My car is a 2012 A4 avant 2.0 tdi black edition.

Can anyone tell me what relay 645 in the ECU box is for?

It keeps switching on and off when the ignition is off and as a result drains my battery overnight. I’ve swapped it out and it’s still switching so the fault appears to be elsewhere and not the relay itself. 

 

Thanks for any help you can give. 

 

P