I’ve seen this same post on the XJ threads, but exact same issue. Everything fine on the freeway, AC blows ice cold. After a few stop lights on side streets the AC will turn off and within seconds the yellow High Temp message will turn on, then the red High Temp message, then the car goes into Limp Mode. I just spent $2000 to have the water pump and all hoses replaced. Next morning, same exact overheating. ANY IDEAS???

 

Radiator/condenser fan. Your speed provides enough airflow to cool, but at slow speeds the fan(s) doesn't provide enough/any airflow.
There are members who know this problem, and there are fixes. I will let them speak their experiences.

 

but why do you let the car overheat that much you need to turn it off asoon as you see the first yellow light😭 that's why these jaguar forums are full of blown engines

 

It’s less than 5sec.

 

Often what is missing from a post is more informative than what is included.

Was it a water pump and/or hose failure incident that prompted the $2000 replacement or was the replacement an attempt to resolve this same issue? An engine that has been overheated just short of serious damage to the heads can be on borrowed time.

First I'd monitor the actual coolant temperature (proactive and accurate) and not wait for the warning lights (reactive and approximate) to find the operating temperature, when it is starting to spike and how fast it rises. The engine has already got way too hot when the warning lights appear but so far you don't know if it's running normally and you're getting a major temperature rise or if it's hot all the time and the peak when you slow down is then sufficient to trigger the warnings.

Graham

 

If your car overheats and you can't stop immediately, try this trick - it might help. Turn your heater on full blast! - maximum heat and fan speed - and open the windows if it gets too hot.

Your heater is a small radiator in the same plumbing circuit that circulates coolant through rubber hoses around the engine (where it absorbs heat) and through the radiator (where that heat is dissipated). Between the engine and radiator is a bypass hose that goes to the heater (which is a small radiator). Turning the heater on dissipates heat from the coolant into the passenger compartment, which helps cool off the engine somewhat. That might give you enough time to find a place to stop and shut the engine before it's damaged.

Always stop as soon as possible if your car overheats.

 

This ..... and turn off the a/c.

Richard

 

I've encountered this issue before, however I monitor my coolant temperature with an OBD2 heads up display on
my windshield. OBD reported normal coolant temperature of 85c, so I knew I wasn't overheating. What can cause this
is a loose ground wire, or a loose battery cable (that was the issue in my case). After reading codes, I did have a pending
for coolant temperature circuit out of range (or something similar) which implies the front temperature sensor was reading
out of range from the rear sensor or visa versa. Provided you have a good water pump and no leaks in your cooling pipes,
this is not a major issue but i'd look at your grounds and battery cables.
turned my car off and then on and all was back to normal after.

Prior to this occuring my infotainment system did a reset on its own due to the loose battery cable, ECU got confused?

 

@Cee Jay You were right!! It was an intermittent failure so they missed it the first time. Another $1600.

 

Slightly off topic but I asked a JLR engineer why they didnt include a temp gauge on the XK. His words, "In the past if you tell a Jag owner that X is normal operating temp and their car goes over that temp, they run to the dealer. Problem is, X might still be normal for a given situation." I think we would all agree that is rubbish and is the reason I still have an OBD dongle and an old cell phone loaded with an OBD software app to read coolant temps in real time.

 

That's why the X100 does have a temperature gauge and an oil pressure gauge which always read the middle of the scale irrespective of what the engine is actually doing. It's ridiculous.

Richard

 

Ho Lee ***! That is some super grade clandestine fuqery right there my friend.

 

Those X100 gauges are not actually GAUGES, they are basically idiot lights. Most new car 'gauges' operate the same way... they are stuck in NORMAL range unless something goes very wrong.

 

You could well say, they report “fake news”…

 

Huh? Foolishness. Even the "idiot light" gauges still serve a purpose and still work when things go wrong as Cee Jay points out.

 

Happened to me.
The senor that turns the fan on was shot-- and yes, a pricey fix. Glad you got it sorted.
The only thing I'll say in opposition to some comments (for anyone else who reads) is I was on an LA freeway at the time, and I knew traffic would clear when we crested the hill. Like you, the warning went to red only for a few seconds, and when we picked up speed on the downhill it went to yellow then disappeared. As I was only headed to a spot about a mile from the offramp, I made it home with no reappearance of any warning light.
However, I took the always-reliable advice of another forum member and chose to put the car on a flatbed and have it brought to the dealer rather than risk more high temps.

Looking back... given that the fans never turned on... it's interesting how quickly the alert went away. Guess it's a testament to the efficiency of the water pump, which kept circulating coolant the whole time.

 

Well, well, I did not say they are useless. But they do give a false sense of security and may be misleading the driver while temp has already been rising. I guess I have to express my dislike for that kind of “information”. No less, but also no more.

 

Sounds stupid to say. But it sound like you have low coolant. Some time looking at over flow coolant tank will throw you off. Try filling it with coolant from radiator.
I changed my water pump my self on srt for the third time, and could not figure out why it was running hot. I didnt have enough coolant. Im just saying please let us know if that the case.lol im just saying coolant low. If not check those bottom hoeses.

 

Yes, checking my coolant level was the first thing I did.
Got the car back this morning. Replacing the water pump and all the hoses didn’t do the trick. Still overheated first time I took it out. The fan was intermittently failing. Now that the fan is replaced everything is good again.

 

it works very well and kept people out of the dealer service department. 115c is well before any damage happens, fans are screaming way before.

when you have a chevy cruze moment and try to drive with no coolant is when things go wrong. the only cars that can drive with no coolant are fords with cht sensors