High temperature

[BSharp]

I have posted this problem before on T5 forum but I still can’t get to bottom of it was hoping for some assistance here is poss
has anybody experienced these symptoms.
1) high coolant temperature around 110 degrees!!!!
2) fan running after engine turned off.

the only way I can check coolant temp is via a dongle in OBD11 socket (no temp gauge on my van) I appreciate this may not be 100% accurate but I assume the temp is high as fan is running full speed.
It’s been with mechanic had new water pump, timing belt And temp sensor but the symptoms are still the same?? If anybody has had similar it may help me get this sorted

 

[DaveD]

Have you replaced the thermostat? I thought that would have been top of the list of suspects.

 

[BSharp]

How’s is the best way to check thermostat? I presume if it’s stuck closed then the engine would overheat and if stuck open never get to temp, mechanic seemed to think that coolant was flowing around the system so ruled this out but I think for the cost I’ll get this changed.

 

[DaveD]

The thermostat might not be fully opening when the engine reaches normal operating temperature, restricting the flow of coolant into the radiator, rather than check it, which involves removing it, I'd just replace it, the cost is minimal.
And I'd replace the mechanic too.

 

[mmi]

I have posted this problem before on T5 forum but I still can’t get to bottom of it was hoping for some assistance here is poss
has anybody experienced these symptoms.
1) high coolant temperature around 110 degrees!!!!
2) fan running after engine turned off.

the only way I can check coolant temp is via a dongle in OBD11 socket (no temp gauge on my van) I appreciate this may not be 100% accurate but I assume the temp is high as fan is running full speed.
It’s been with mechanic had new water pump, timing belt And temp sensor but the symptoms are still the same?? If anybody has had similar it may help me get this sorted

What engine you've got? Engine code would be the most helpful. It's on a sticker under dash (or service book) - something like CAAB, CXFA,...

What kind of dongle you have? Did the mechanic verify the reading with a different tool?

EDIT: Just a plot how coolant temperature should behave - CXFA engine (110kW/150PS). Expecting the behaviour to be similar on all T6 diesel engines. The plot is just a half of my regular daily travel, first 3 mins at 40km/h then at steady 90km/h, and last 8 mins cruising at 60km/h. Temperature logged at 1 min intervals.

 

[BSharp]

Thanks for all replies very informative. Just a quick update I’ve just taken van for test drive and again showing high temp “apparently” 110-115 degrees??? So I took some readings using an IR thermometer and actual temps are actually only around 60-65 (I know they are low) and fan running constantly, I presume this is what is lowering the actual temp below the 90degrees. So I’m conclusion I suspect a faulty sensor which is giving the false high temp reading and causing fan to run. Although temp sensor was changed there is a second sensor which has been over looked I’m optimistic this is issue.