2016 Octavia Towbar Wiring CAN Issue

Hi 

I've installed a Westfalia towbar with the dedicated wiring harness pinned directly into the BCM and coding done via VCDS. (I used Sasha Grace's guide which worked perfectly.)

Initially everything worked perfectly with no glitches. A few days later I now have an engine start/stop fault when I start the car and my parking sensors aren't working, I just get the long beep and screen says park pilot isn't available. 

Control module in the boot has a solid red light which was previously a green light. 

Spoke to PF Jones support who said the check the CAN signal on the yellow/black wire in the boot where I currently have 0v. Earth is good. 

OBDeleven says there is no CAN communication with the trailer control module. 

Has anyone had a similar issue, I assume the wiring and coding is correct as initially everything was working.