2.0 CR Temperature fluctuations, thermostat done but still not resolved

[bintyandthebeas]

Hi all,
I have a 2011 2.0 common rail 140bhp which is having temperature issues. If it makes a difference it has a DSG box and is on 84k. Serviced at max 10k intervals, cambelt done at 54k with water pump.
For the past few months the temp gauge will not reach 90°, but instead hovers from 65° downhill to 80° uphill. Occasionally it will jump in to life and heat to 90° and sit rock solid (maybe 1 in 5 journeys). There's no error showing on Vagcom (except a new one this week advising a glow plug issue with no1 plug).
As expected, inside fan temperature is lower than hoped for and increases when going uphill. I assumed it was the thermostat so had this replaced (at great cost!!) earlier this week with another new genuine stat. Turns out it's located at the back of the block and buried deep. Coolant was obviously replaced and again genuine stuff used.
For the first couple of days it was fine and I thought the issue was sorted, but yesterday and today I'm back to the same problem again.
I'm struggling to find a coolant temperature sensor, but assume this to be the issue, or a wiring fault.
The car is used daily for work 40 motorway miles away, so it has plenty of time to heat, it just refused to do so!
Can anybody help?

[rowdy-999]

Hi all,
I have a 2011 2.0 common rail 140bhp which is having temperature issues. If it makes a difference it has a DSG box and is on 84k. Serviced at max 10k intervals, cambelt done at 54k with water pump.
For the past few months the temp gauge will not reach 90°, but instead hovers from 65° downhill to 80° uphill. Occasionally it will jump in to life and heat to 90° and sit rock solid (maybe 1 in 5 journeys). There's no sales showing on Vagcom (except a new one this week advising a glow plug issue with no1 plug).
As expected, fan temperature is lower than hoped for and increases when going uphill. I assumed it was the thermostat so had this replaced (at great cost!!) earlier this week with another genuine stat. Turns out it's located at the back of the block and buried deep. Coolant was obviously replaced and again genuine stuff used.
For the first couple of days it was fine and I thought the issue was sorted, but yesterday and today I'm back to the same problem again.
I'm struggling to find a coolant temperature sensor, but assume this to be the issue, or a wiring fault.
The car is used daily for work 40 motorway miles away, so it has plenty of time to heat, it just refused to do so!
Can anybody help?

Welcome.

Does the heater blow hot air? Radiator not feel warm?

[bintyandthebeas]

Thanks for the reply!

Blower temperature fluctuates in line with the temperature on the gauge. This morning it wasn't getting over 60, so even at highest setting it was barely warm.

[rowdy-999]

If that's the case then changing the coolant temp sensor won't change anything.
It could be an air-lock, faulty water pump or radiator to blame.

[bintyandthebeas]

Thanks again.

Would I be wrong in thinking that this would mean the car would be overheating, not too cold?

I really should be checking to see whetheer the fan is on when I pull up but the engine cold, but my journeys today saw the temp gauge sitting bang on 90 degrees, and fuel economy was good. Hopefully(?!) it will be cool again tomorrow and I can check then.

[bintyandthebeas]

Update: Still not resolved.

Another full coolant replacement has been made and garage has had the radiator out. Water pump replaced early last year, so my mechanic is ruling this out. He tells me the engine would overheat, not be too cold if it was the waterpump.

It was -4 this morning and after my 40 mile commute to work the gauge was barely registering at just over 60 degrees.

Nothing is showing up on VAGCOM when plugged in (other than a headlight bulb stored fault for a couple of weeks ago), so I am at a loss.

Next thoughts are a replacement battery as car is coming on for 6 years and he thinks this may help. There's some logic to this as sometimes (not always) I can pull over, remove the key and start again and it will resolve.

Any thoughts before I spend a small fortune on a shockingly expensive stop/start battery and have to get it coded in by my mechanic?

[bintyandthebeas]

Another post has been raised by "Kimken" https://www.vwaudiforum.co.uk/forum/s...ue-Need-advise
Sounds familiar!
Should I look at the inline thermostat next? If so, any chance of some help with the part number, or can I assume it will be the same one as mentioned in the other thread?

[bintyandthebeas]

Just confirming the inline thermostat was the problem. I had it changed and the car is driving perfectly and temperature is bang on 90° after heating up.
Part number is 1KO 121 113 A and is specific to cars with a DSG gearbox.
Due to how the clips are located my mechanic didn't enjoy the job, but it didn't take long after removing the air box to get access.

[Darks]

I had this same issue with my MY12 built 125kw DSG. Changed the thermostat through my indy and then had to go to VW as the issue was still happening. Here in Oz it was an issue with MY12 but the dealer's here kept it on the low.

Just confirming the inline thermostat was the problem. I had it changed and the car is driving perfectly and temperature is bang on 90° after heating up.
Part number is 1KO 121 113 A and is specific to cars with a DSG gearbox.
Due to how the clips are located my mechanic didn't enjoy the job, but it didn't take long after removing the air box to get access.