This past weekend I got the bright idea or so i thought to flush out my old coolant and put in fresh.......I got the xjr about 18 months ago and had no idea exactly what type of coolant was in the car or when it had been changed. A PH test done indicated it was time to renew. I drained the coolant through the bottom hose on the radiator, on the second drain the low coolant light appeared when I started up to circulate the water. Filled and drained a total of 4 times before adding 2 jugs of new coolant and topping off with deionized water. The low coolant light continued to be illuminated through all drains after the first. I have went out for several drives since and other than the first where I needed to add about 12 oz. of water the level in the expansion tank has been bang on. I disconnected the negative battery terminal for about 30 minutes hoping this might reset the warning light but no luck. From what I can find there is only 1 sensor and it is in the expansion tank. Is it just a case of bad luck that somehow i buggered the sensor in the drain and fill process or might it reset after some time or do any of the learned bunch on the forum have any suggestions of what else could be tried........thanks

 

I'm assuming the coolant reservoir and coolant level sensor design is the same as on the X300: I'd check the coolant level sensor for positioning and connectivity. You might have bumped the sensor out of place. It fits in a slot in the underside of the reservoir and if not positioned perfectly, will show the radiator light on the dash. Then check to see if the sensor is still plugged into the wiring connector correctly/securely.

Lastly, I'd look for a water leak. Might be that the sensor is positioned and connected and doing it's job after all.

 

Upon further research I am seeing some talk of a sticking magnetic float in some overflow tanks in addition to a sensor I am wondering if anyone can tell me if such a float is present in x300 overflow tanks and if so any idea of where in the tank as opposed to the probe itself it is situated.

 

Yes sir, the float on the inside of the expansion tank can stick down after a drain, which keeps that light activated. The float can barely be seen inside the filler cap, it is a white donut, that when floating will keep the coolant light off. You can free it up by carefully prying with a stiff wire and flashlight. If you aren't losing coolant, this is most likely the scenario. I've seen it three times on my own vehicles. The sensor itself is actually outside of the tank but has a probe that this donut on the inside of the tank activates. Obviously a very important telltale that you want to work correctly!

 

Please promise not to use that font again - I'm still feeling as if a migraine's coming on!!

 

lol!!!

 

Sorry at least now I''m not the only one with a headache............

 

I see the white donut you speak of, a stiff wire and I are heading to the garage right now

 

It worked thank you so very much

 

Having the same problem and I just haven't gotten around to correcting it. Thanx for bringing it up and the solution.