I have a 2017 XF AWD with a 2.0 diesel engine. I must say the car is excellent and has been nothing but a joy. However, for quite some time it has had a P0128 code locked in. I understand that it is most likely a stuck open thermostat. The engine does run below normal temperature for quite some time before coming up to the usual halfway mark. It never exceeds that temperature, so I'm happy for that. However, I do realize that if it is stuck open, it could someday stick shut. Therefore, I have bought a new thermostat for it and plan to change it out.
Looking at the manual, it seems easy enough to do, albeit with four hoses and two electrical connections. However, they must have had their model engine on a stand, as in the car it seems like very tight quarters to do this job.
So my question is this. Has anyone done this particular thermostat replacement? If so, can you give me any pointers as to what peripheral items need to get out of the way, and tell me if it can all be done from up top, or should some be from down below?
Just want to get my ducks in a row before I take this on. This is by far the most involved thermostat replacement I have ever done. Hopefully, it only appears so.
I have seen several youtube videos, but none are the right unit and engine.

 

I’m in the same situation you are in as well, searching every where for information on how to do this while waiting for delivery of the new thermostat. Any info is greatly appreciated.

 

After looking long and hard at this task, and considering the lack of advice, I have returned the thermostat. It is not worth getting in a jackpot with hose connections, etc., being so inaccessible. I did notice that it "may be possible" to get good access through the wheel well, though the spring would be in the way. If I ever figure out a method, I will post it here.

 

So we're all on the same page...

 

I just noticed the clip left of center in the photo. I wonder if that allows removal of the left portion? That would make things a bit more doable. When you get your thermostat, let me know what you think.

 

I will do that, I think the part is due in 7/17. I flushed the coolant last week, but unfortunately you can only flush about half the coolant, the rest sits in the heater box and in the engine. So only put in just over a gallon on the refill. Will do it again when i take on the thermostat replacement. The Jag dealership said to diagnose it was $195, even though I told them the code was P0128.

 

I have the same issue on my 2017 2.0 D XF
I don't have the code reader but the temp takes miles to warm up - then ok.
I located the thermostat unit online and thought I would give it a go.
There is step by step instructions in the service manual which someone has posted on this site and can be downloaded for free.
You will need a set of hose clamp pliers available on amazon cheap ( $18.00 Canadian Dollars ) its a great tool.
That all being said I could not access the wire plugs to undo - perhaps needs access from below. I did get as far as removing the hoses - all 4 then gave up.
Ill drop it off for a mechanic to do it before winter. I found removing the Air Filter Box and the reservoir gave me a little more room to work and its just a few clips and bolts.

 

This is the thermostat removal portion of the FSM

 

If nothing else, I learned about a great tool and just ordered it. Could have really come in handy about a hundred times in the past!

 

Thanks. I have that manual. They make it look much much easier than it really is. Their engine must be removed or something.

 

I obviously didn’t get the correct part. I told O’reilly’s the correct model, year, and engine. But they didn’t order the correct part. Very frustrating

 

Well, that sucks.
Advance Auto gave me the correct one for about half of the usual price elsewhere...including O'Reilly's.

 

Did you get the right one yet?

 

Impossible to complete without this tool!!!’

 

Here is what I found to be the best method IMO, 1. Disconnect battery in trunk
2. siphon out the coolant in the surge tank and remove surge tank. There is electrical connector on the bottom for coolant level. Easy to remove raise metal clip and squeeze off. Definitely put a pan under the vehicle to catch coolant in the hoses and tstat housing. You could drain from pitcock in the radiator but I choose not to do that.
3. Remove air filter box
4. Remove bolt that secures the oil dipstick to the engine.
5. There are squeeze clamps connecting the hoses to the tstat housing and you will need that tool to remove the hoses. On the other end of the hoses that connect to the upper radiator and the lower hoses they are secured with a metal clip. Lift the clips up or remove them and those hoses will come right off with minimal force.
6. You will need to disconnect a couple electrical connectors: alternator sensing wire(rear of alternator) cold air intake sensor(MAF)in filter box.
7. The mounting bolt size for the tstat housing are 8mm, you will need an extension and a ratchet to remove the four bolts. The easiest ones to to remove are the rear ones and the lower forward one. The forward upper I found to be a little more difficult because the hose is in the way and it is right between the rear of the alternator and the tstat housing bolt. I was able to pull the hose out of the way enough once I disconnected the alternator sensing wire.
8. Once the tstat is free from the block you will need to remove the two connectors that are connected to the built in temp sensors into the tstat. I found it easier to push the red lock tabs back from the connectors with a small pick and then use the same pick to lift the lock and pull the connectors apart.
9. Plug in electrical connectors on new tstat and follow the previous steps in reverse order.

FYI- there is no access from under the vehicle or thru the wheel well that make it easier. Good luck!!! I’m not a mechanic but it probably took me 3 to 4 hours to do it.

 

I also removed the ground cable too

 

Also the check engine light has not gone off yet. I’m not sure if it will clear after so many ignition cycles?

 

8/17 the check engine light went off on our way home from dinner.