Car not coming up to temperature

[Calliemk5]

Hi folks, hope you can point me in the right direction.
I have a 09 dsg that only gets up to about 60deg even after 30 mins driving. Mechanic has replaced the thermostat and both inline sensors, but it hasn’t fixed it. All genuine parts. He said that he checked  the software after the thermostat was replaced and it was reading 90 deg..but didn’t check the gauge in the car I suppose. Mpg of the car isn’t great either. Would welcome your thoughts!

[GVK]

Genuine stats used?

[Mattt]

How long has this problem been happening/when did it start?
I sense a small implication that it could be running rich by the low temp+low mpg. BUT
You can only answer those questions with a decent mech and live diagnostics.
If he checked the ‘software’ then did he do a full DTC scan of the car and observe other readings while the engine was running ie fuel trims etc. If any other codes were stored, what were they?
If this has been a problem since you owned the car (ie fault started during unknown events/interactions) it’s harder to pin down the problem. If your mech didn’t ask the questions I did and possibly a few more find a new mech.
Also as above, with VW, always use the genuine stat, so many problems seem to arise from aftermarket ones it’s just not worth the risk imo.

[Calliemk5]

Yep, all genuine parts used, incl thermostat. The temp had been low for the last 6 months or so, can’t remember when it started.
I was getting the clutch changed so I asked him to look at the temp issue also. He found that the thermostat was stuck open, so he obviously thought  that this was the problem.
Ill ask about the DTC scan to see what else came up, could these explain the low temp though?

[Calliemk5]

Ok, thinking it’s the thermostat now.  Started car this morning, after a few mins checked the hose to the rad. Could feel Warm Water going to the rad. From what I understand this shouldn’t happen until the temp reached 90 deg. Back to the mechanic I suppose.

[pudding]

Bear in mind DSG has 2 thermostats.  A main one under the alternator like all GTIs, and a secondary one above the gearbox. 

Manuals only have one stat.

Perhaps back to the mechanic to check/replace the second stat?

Having said that, I think *some* DSGs also only have one stat, it's a typical VAG change over year thing.