steve_c
Grumpy OAP & A2OC Donor
I suspect the fault codes you are getting are unrelated to the actual fault and are simply a consequence of the low voltage due to the fault.
To rule out the hazard relay you could disconnect it using the A2OC approved "make a fist" method when you are done using the car for the day. In the morning, if the battery hasn't gone flat you know the relay is the culprit. Additionally, there shouldn't be any fault codes. Diagnosis... villainous relay causing hazards to flatten battery and giving spurious fault codes and plenty of misdirection.
Unfortunately this is not a regularly recurring problem. Rather, it happens occasionally, quite at random. Other times, the battery appears to maintain a good charge. So, disconnecting the hazard relay overnight would tell me nothing.
It's a pain, not knowing whether or not the car will work when I go out to it. If I have to get to the back seat to access the manual tailgate release that is a real challenge and takes an absolute age. Swapping the batteries over is the easy part.
My A2 is an absolute lifeline for me, so I hope I get to the bottom of this before too long.