Engine not Reaching Temperature

[edens]

My car is a B8.5 2.0TDi 177PS CGLC engine with 7 speed s-tronic gearbox.
I have an issue where my engine temp wont stay on 90 degrees Celsius. According to the OBD scanner it's mostly in the 60s and 70s and seems to fluctuate.

I've read lots of posts similar, mainly for different engines and seen people replace various parts with no lucky so I wanted to start a threat with my specific details.

I did replace the timing belt, water pump, alternator and idlers only a couple of weeks back so I have checked the cooling system for air, but fairly sure it's not that and the engine has covered about 500 miles with no loss of coolant.

I've read several posts on the internet about a secondary thermostat or inline valve, but I can't see anything that looks like the pictures I've seen of it, so my first question is whether my car would have this?

I believe the next thing would be the temp sensor, however, I'm struggling to locate it, I think possibly at the rear, but if it is what I think it is, I'm not sure how easy it would be to remove, can anyone confirm the location? Also, given it's proving a reading via the scanner, it makes me think it probably isn't faulty.

This I guess leaves only the thermostat, but before I spend more money and time I wanted to get thoughts on the best approach.

Just to add, there is no noticeable issue with cabin temperature, it's still getting hot in there.

Thanks.

[Roverfan]

With my Golf after investigating this issue many years ago I concluded that 'Diesels just run cold unless under heavy load'. The cooling system is designed to handle peak requirements (high load) so when we cruise (low engine load) with heaters on in cold weather, the cooling system is too efficient for the heat produced. On mine it tends to stick at 90 on the gauge if I don't have my heaters on and the car is being driven.

If your symptoms are similar I'd say there is no fault

[edens]

With my Golf after investigating this issue many years ago I concluded that 'Diesels just run cold unless under heavy load'. The cooling system is designed to handle peak requirements (high load) so when we cruise (low engine load) with heaters on in cold weather, the cooling system is too efficient for the heat produced. On mine it tends to stick at 90 on the gauge if I don't have my heaters on and the car is being driven.

If your symptoms are similar I'd say there is no fault

Thanks, I have seen a lot of people say this also. However I'm 80% sure that it used to reach and stay at 90, though I'm starting to question myself! Again I may be imagining it but it seems like fuel economy has dropped a little.

[Crasher]

Pay little attention to what the gauge displays, in reality it shows 90 at a real 77 and still displays 90 at a real 117, before shooting up at at a real 118.

[edens]

Pay little attention to what the gauge displays, in reality it shows 90 at a real 77 and still displays 90 at a real 117, before shooting up at at a real 118.

I'd read that was the case, so have been using the real time OBD reading, it's rarely getting beyond the 70's. Despite what some people have said about them running cool, I'm fairly sure something doesn't seem right to me.
I'm interested to get others thoughts on this and confirmation of the sensor location and whether it has the second thermostat/ valve.

[Crasher]

What is the VIN?

[edens]

What is the VIN?

I can check in a couple of days as currently away. Is there any other info aside from the details I provided that would be useful to know before I get the VIN.