Slow to get up to temperature

[A8 PMJ]

Hi all, I hope I am not being a pain.
Can you please shed some light on a problem I have discovered. With an ambient temperature of below 10 C, it can take up to 20 miles for the car to reach running temperature on the gauge.
It could be as simple as the Thermostat stuck open, but I believe there is a second Thermostat that opens to feed water to the transmission, to cool the oil, does such a thing exist? this could also be at fault.
Has anyone had any experience of this problem and what fixed it?
Any help would be appreciated.
Pat J.

[snapdragon]

Yes, what year and engine?

[A8 PMJ]

Registered 2014 but it is a 2013 model, 4.2TDi 350 BHP. CDSB engine.

[A8Cruiser]

One of my D4s had an open valve/thermostat for the gearbox and oil cooling system.

However, id did not affect the car getting up to temp at all (coolant temp wise anyway).
i think it just affected the gearbox oil cooling.

Does your car warm up quicker if you turn the climate control to Econ mode or even Off completely?

[A8 PMJ]

Tried it today with the Climate switched off and it took roughly the same time.

[A8Cruiser]

Might be easiest to replace the temp sender first.
i think it sits at the top of the engine and should be reachable once the plastic cover is removed.

check the Etka on line for the exact location. If it is where I said, then it is a 10 - 20 minute job if that.