I've read a few posts about battery/alternator based issues and was not surprised to get the 'hdc inactive' error message a couple of moths ago. A few days later I had a completely dead battery. As advised from here I bought the Bosch S5 battery, which is a sizeable lump and only just fits in the battery bay and the old one was not even half the size so no wonder it gave up the ghost. I was now left thinking thats the end of my battery issue for the next 200 years based on the size of the new battery

o..m..g that darn 'hdc inactive' message came back as soon as the weather turned really cold and i was pretty gutted, but the battery hasn't (fingers crossed) gone dead. so a scan through the forum on possibles and concluded its a drain overnight because once started in the day, i wasn't getting a repeat failure at all, so whats the cause?

Without fail everyday early in the morning (0530) i've been getting '(bong) hdc inactive' so racked my brain to think what could drain overnight, and whilst listening to steve allen on LBC had an idea .... the radio

I've physically switched the radio off overnight before switching off ignition and it may be an amazing coincidence but no 'hdc inactive' for the last 4 days

This may not work for anybody else, but it may be something to consider if youre having a battery drain. 2007 3.0L Diesel VW Touareg SE
2003 4.4 LPG, Vogue, Silver

Thats an interesting observation.

@ twhincup I'll go along with what you said. Been having battery drain myself so took the car for a long (about 45 mins) drive last night and turned every thing off.

This morning got in a warm car (FBH on for 10 mins ) and started with no hesitation.

I even turned my screen off

Interesting, may be a solution to a few battery drain problems. How its doing it is unanswered but sounds
Like it could be the culprit. There is nothing that can't be fixed with a hammer😜😜
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could it be that that particular ecu is taking to long to shut down. ... - .- -.




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I've done some measurements on this and on my car I can find no difference in potential current drain between turning the radio off before or after turning off the ignition.
Based on the above it appears when you turn the radio off has no bearing on level of current drain once the car has gone to sleep.
Unless someone knows differently.....
One source of current drain I did find some time ago relates to the LR telephone installation.
I found a current drain of 140mA when the car was asleep on Fuse 22.
Removing the fuse reduced this drain to 0mA.
Given that I don't use the installed, now somewhat old fashioned telephone, removing the fuse seems to be a good option.