Engine temp high warning light

07 XK. First warmer day here in the NE, 80 sunny no humidity. I was parked for ~15 minutes, AC on and the high engine temp high warning light came on. I turned the ignition off, cooling fans are working and continued for a few minutes afterwards. Restarted after ~15 minutes, no warning light. Drove to my shop guys close by, replicated what happened and the same thing occurred. Checked coolant, just below minimum level but the low coolant warning did not proceed engine temp high warning. Thoughts? Temp gauge? Water pump? Thanks!

Are you going to be repairing it yourself or will the shop be doing the work? My first thoughts would be either a thermostat that is getting stuck closed or a bad coolant temp sensor. If it is one of those options, either should be fairly easy to diagnose.

I wouldn’t be fixing it, beyond my limited mechanical abilities… How does one diagnose the two potential issues you mention?

The thermostat iz a common failure point. The rubber seal pulls off the valve. Three bolts to undo and check. Usually this failure causes a low coolant temp warning though.

With your car dead cool in the morning, pull out your OBD tester and read the coolant temp. Does it seem close to ambient? I ran into this failure on an x100. It said it was overheating but with none of the suspected symptoms. Changing out the (cheap) sensor lowered the temps 25°.

Mminnich beat me to it. I’ll add that the thermostat is usually cheap enough and easy to change that most people will just change it regardless.

I will check into it, I figured thermostat or water pump, common culprits on many cars at this age. Thank you!

Please give us an update once you know more. I’m curious what it turns out to be.

I use an indy shop that gives me fair pricing so I’m going to proactively replace the thermostat & housing and the water pump, ordered parts earlier today. I have no clue when either was done. I will update on the condition of each once completed. As always, the advice is appreciated!

So, ordered a thermostat + housing and water pump (Gates - metal impeller & gasket), 2 other water pumps I looked at had composite impellers which my shop guys were not fond of. I read pluses and minuses on both but elected to go with the metal impeller. Regarding the thermostat, good thing I ordered the thermostat + housing, my guys said the existing housing was installed improperly with an incorrect bolt and was challenging to remove, i.e., was likely mangled upon removal. I ordered the housing in the first place because from what I had researched, they have a tendency to wear out over time.

Got the car back Thursday and have had no “engine heat high” light come on and today I drove about 40+ miles in 94 degree weather, AC blowing, no issue. As a final note, before the work was done, I noted that my cooling fans were coming on often. Today, even with the hot temps, didn’t hear them at all. Thanks for all the help!

That’s great to hear. Sounds like that probably fixed the issue. Now go enjoy the beautiful weather in your car. Thanks for the update.