Hi fellow owners, I hope you can help please,

I have a 2012 Audi A6 2.0 TDi multitronic with 67,000 trouble free miles on the clock. A while ago, I noticed that the engine temperature gauge seemed to be taking a long time to rise above the 50 degree mark. I ignored it for a while but then also noticed that on longer motorway journeys, when the temperature did eventually get up to 90, if I left the motorway for slower roads, or even passed through a 50 mph roadworks zone, the temp gauge would start to drop off, down to 70 or 80 degrees.

My morning commute is through town & therefore the engine rarely gets over 2000 rpm. However, on bad days, this can be up to 25 minutes in slow stop-start traffic. In these conditions the temp never leaves the 50 degree zone. I have deduced that putting the gearbox into sport or manual mode (rather than standard eco) does bring the temp up a little quicker, but still doesn’t stop it dropping down again during easier driving. I’ve not actually tried this, but suspect I could leave the car idling on the driveway for hours without the temp gauge ever moving.

The car has been into the garage on a number of occasions. The thermostat has been changed, all the relevant pipework flushed & cleaned, I’m told the heating matrix is fine, the water pump was only recently changed (with the timing belt) but nothing has changed the lack of heat in the engine. I have not had the Diesel-gate software update. There are no other apparent side effects and the diagnostics shows nothing wrong.

I know it’s cold out there, but I don’t believe my engine is behaving normally. Any ideas please?

Thanks.