So, driving in to work today and I see the check engine light is on. First time for my Jag. Car is still running fine. I will read it when I get home tonight. Hope it is a gas cap or something simple.

Stay tuned.

 

I am thinking, the last time I drove the car was last Friday. We had a ton of rain last Thursday and Friday, and I drove through some relatively high water, particularly on Thursday. I am wondering if the check engine light may be a result of that. Maybe wet air filter? Some other water related issue? Car had no light until today.

I will know more after I read the code, but it has my mind wandering.

 

Just read the codes. Don't clear them at this stage.

The reasons not are that you also clear the OBD monitors and so:
1. you may then be in Catch-22 where no further codes flag and you can't get the monitors to set - makes diagnosis hard!
2. if you have them, you'll fail smog tests

 

It turned out to be P0128, which is low coolant temperature. Living in Louisiana, the last thing you might expect is LOW coolant temperature

So possibly the thermostat is bad, or possibly it is a gremlin. I reset it and will see if it pops back up again. It did not come on during the ride-in this morning.

 

Thermostat. Rubber gasket distorts and blocks the thermostat from closing. Been there, done that.

 

How difficult is it to get-to/replace? Also, is there a metal housing available for it (I am assuming it is currently plastic)? What else should be done while I do this repair. Hoses? Belts? Other? (Assuming the light comes back on)

I have not so much as pulled the cover off the engine on this car, which has been nice. Looks like it is about time to get my hands dirty.

 

Yep, plus you're cursed with the XK's plastic version so get the whole shooting match from the block up. There's a couple threads out there. Not a horrible job except for the bolts into the block. At the same time, the T stat is probably stuck so you don't want to drive it in the heat before fixing it.

 

I am assuming it is stuck open, so is this a problem? It is my daily driver and I really don't have an alternative mode of transportation.

 

The t-stat housing broke off inside (plastic sucks) on my 07 and I had the same symptom. I purchased the new housing with t-stat & temp sender complete (pretty sure I got it at rockauto.com). It was a PIA to remove & install in that the throttle body had to be removed for access and I kept dropping the lower bolts. It would have been easier to stuff rags under the housing so that dropped bolts could be retreaved easier otherwise they made their way clear to the lower engine cover. (hence the PIA)

 

If you have the normally aspirated engine, there is no metal water outlet available. As others have suggested, replace the water outlet assembly, which contains a new thermostat and water temp sensor.

It may also be best to remove the inlet manifold and replace the coolant hose that comes up to the throttle body and the others to the EGR valve as they are prone to failure. With the inlet manifold removed, access to the water outlet bolts at the block are also easier.

 

Good to see you back and know that you are naturally aspirating.

 

The light has not returned. So I guess at least, for the moment, all is good.

 

Just once in my life I'd love to see a Low Coolant Temperature light come on in my Pantera instead of the usual overheating light just before it vapor locks and strands me for 20 minutes while it cools off.

 

I much prefer a low coolant temperature light to a high coolant temperature light.

I am wondering, when the XK overheats, do you get a separate temperature light or just the check engine light? Because I typically do not panic over a check engine light but I would with a high temp light and would take quick action. With the check engine light, I drove to work and drove home again before I checked it out. That could be fatal (to the car) if it was high temperature.

 

See these threads:
1. See posts by 'Patrick Wong' in this thread:
https://www.jaguarforums.com/forum/x...-xk-na-206609/

2. See posts by 'Hailers' in this thread:
https://www.jaguarforums.com/forum/x...rmostat-97933/

That second thread is the one I went by when I replaced mine several years ago.

I drove mine for a while with the 'under temperature' code, until I got the replacement parts.
To be safe, get yourself an OBD reader so you can monitor your temps from your smartphone while driving.