Not Holding Temperature

[Kap]

Hey Lovely People!

I have a 2011 2.0 Petrol Scirocco which has given me 6 years of hassle free driving.
She's on 107k now so I guess its problem time, the first of which is as follows:
Once the engine has reached 90 on the Temperature Gauge if I blast the heating on full whack the gauge will drop significantly (around 2 bars) and then struggle to go back up, The needle will also drop whilst idling.
If I put the blowers on lower the gauge wont drop but I can feel the heaters aren't as hot as before I noticed this issue.
I have had the Thermostat replaced but to no avail.
I have done my own research and have found others reporting the same issue within the VAG community but they all have slightly different engines.
My next point of call was to have both coolant sensors replaced but I have also read about a non-return valve in the coolant system which could be failing.
Can anyone confirm if the 2.0 Petrol Tsi is fitted with a non-return valve.

Any help would be appreciated.

P.S I know many people are saying that its normal due to the cold temperature and the system drawing cold fluid but I've driven the car as a daily and have never experienced what I am experiencing at the moment so I know something has changed.

[Fury1945]

It's running cold with the thermostat stuck open. Thermostat may need replacing.

[Kap]

Thanks but Thermostat has already been replaced last week and its not fixed it.

[Fury1945]

Oh I've got the same problem and have booked a thermostat change. I'm looking into whether there's a second thermostat for the dsg gearbox see youtube. When I rang the garage they said it doesn't exist on a scirocco but I'm not convinced. Is yours fixed?

[Fury1945]

You didn't mention a thermostat change in your first post. Its quite important to share all info so people don't waste time. There isn't a second thermostat for the DSG.