Glow Plug Control Module
 

I'm having trouble starting the engine when warm, usually when making a couple of stops it'll struggle to turn over. A scan has shown the glow plug control module to have a fault, see image.

The issue I have is I don't know where this is located or what it looks like on a 2011 4.2tdi Q7! Is it a relay (in the relay box under the bonnet) or an actual module maybe under the ECU? Any help would be appreciated.

I guess another thing would be, could something else be causing this fault to show?

Attachment 30103

That voltage 8.44V looks a bit low, that would explain the struggle to turn over and the error might be just the result of low voltage. Check the battery condition and charge level and connections from battery

According to ETKA, it is indeed a relay, where you stated. The part number depends on engine code, which are as follows for the 4.2tdi:

CCFA - Part# 038907281B or 04L907282B - stamped 457
CCFC - Part# 4L1907282 or 4L1907282A - stamped 652

I would double check which you have before proceeding (as ETKA can sometimes be wrong).

I thought that too, battery health according to MMI was 90% but might not be a very reliable indicator, perhaps it's dropping voltage after a couple of starts with short journeys. I wish they had kept the voltage gauge in cars!

It's an EFB battery about a year old but has been run down a few times due to an electrical drain somewhere.

Thanks. Mine is CCFC. I'll check it before ordering of course. It might just be the battery not providing enough volts though, might need to test a bit more. Will monitor the battery voltage and do some stop starts. I have a boost pack handy.