I'd been getting implausible signal/signal too high indications from my cooling system for a couple of years, but only in winter. When it first happened, I scanned the car and watched what I thought were the two coolant sensors, and it showed both rising from cold, pointing to a thermostat stuck in the open position. I'd been waiting on a timing belt change to do the thermostat, but at the weekend decided to change the G62 anyway. I changed it, reset the CEL, and it solved the problem. I then scanned all 10 coolant labels on the test drive and all of them started rising from cold. I think this means that I'm unable to see the G62 from VCDS.