"low Coolant" Message On Cluster

[Old Dave]

We bought a 2001 Yukon XL (98K 5.3L) a couple months back and periodically we get a "Low Coolant" message displayed on the message center on the left side of the instrument cluster. The level is fine in the tank, truck is running at the correct operating temp. and it runs fine. This doesn't happen all the time, just occasionally and seems to be only in town. It came on when we coming home Mon. night when I was sitting at a light. It stayed on all the way home (25 miles on the highway). When the light comes on and you shut it off for a minute and restart it the light is off. Sounds like some sensor, maybe in the overflow tank (radiator) that is not working correctly but I haven't investigated that yet. I called two auto parts and they don't show anything. The dealer said there is a sensor that is part of the coolant surge tank (overflow bottle) but it's about $60. Anyone been down this road before?

[WELD4DAYS]

I have a 2002 Silverado and my coolant light comes on also.I top off the over flow tank just above the full line and the light goes away.I'm worried because every few months the light comes on and I have to top it off again.That means the water is dissapearing somewhere.

[Riveted1]

Originally Posted by WELD4DAYS

I have a 2002 Silverado and my coolant light comes on also.I top off the over flow tank just above the full line and the light goes away.I'm worried because every few months the light comes on and I have to top it off again.That means the water is dissapearing somewhere.

These trucks are (supposedly) notorious for their intake manifold gaskets and their water pump gaskets going bad. My '99 does the same thing. Every so often I have to top off the coolant level. Just haven't had the time to look at it.

As far as the original post goes, if your coolant level is fine, then it is probably a bad sensor. Supposed to be as easy as changing a light bulb.

[04 orange]

The low coolant message is going to be the coolant level sensor that is made in the jug. Those were bad about going out on the 99-02 model. For the slow coolant leak check the water pump gaskets those are bad about leaking. There is a new design gasket from gm that works good. The intake has no coolant going through it, when the gasket goes bad they great a vacuum leak and that will set the check engine light most of the time. Also check the freeze plugs in the heads for leaks.

[WLPTMP]

try cleaning the jug out wish dish liquid it might some crap on the sensor

[Huck]

MY 2000 had a slow coolent leak from the back of the engine someplace. At 140,000 miles I had to add some coolent every couple of months or the low cool light would come on. Rather then going nuts with wondering what is leaking, I slowly added some Bar's leak stop to the overflow tank while running ----it was sucked back into the coolent system and the leak stopped. Sold the truck with 180,000 miles with no leak.
Only problem was trying to get the Bar's into the system with NO radiator cap to give you access.

[DavesRide]

FYI. There is a service bulletin for this same condition. Yes, all of the causes posted are reasons. The bulletin is about a crack in the head on a certain casting. You have to remove the valve covers and look at the casting #'s. You can also see the clean spot where coolant slowing runs down into the oil where it evaporates. I have seen a couple and it was built in on some of these trucks. It really doesn't hurt anything other than waste coolant and worry the owner with the light on.

[PrerunnerRob]

My 01 had the same issue, and it was a leaking freeze plug. The leak was super minor, and some stop leak took care of it. I removed the upper radiator hose, dumped it in, ran it, and topped off the coolant level as needed. I thought it was a leaking heater box at first, but noticed the leak I thought I had was from the condensate drain from the AC system.

[CoolFX]

My '02 Z71 has the same problem as WELD4DAYS post above. I can smell the sweet smell of the coolant but can't find much more than a trace on the skid plate. The rest of the engine is dry as a bone. I just keep refilling. My theory is, the problem will only get worse and then I will be able to find it.

My cuz works for a local dealership and he recommended that I replace the orange dexcool antifreeze with the older green coolant. Please note, This action WILL void your warranty! So if your truck is still under warranty don't do this! According to him the orange coolant will "gel" inside your the water passages and eventually harden. I can see traces of the crusty byproduct inside the catch tank now. There is a change out in my future.

[andresco50]

Check for leaks and the water pump too... and take of the coolant jar wash it and install again