The "coolant low" indicator came on today. Since I was already at home when the indicator came on, I opened the hood and could see that the coolant was above the maximum for a cold engine. This is the second time in two weeks or so that this indicator has come on. I noticed today that the engine was very hot even though the car was driven only a short distance. About 4000 miles ago, the water pump, water pipe, seals and intake manifold gaskets were all replaced. I'm thinking the thermostat has to be replaced. The reason is that the car is running hot and the low coolant indicator comes on because the computer thinks that the reason the car is running hot is because the coolant level is low. However, a faulty thermostat can also cause the engine to run hot. Any ideas?

 

Check to see if the float in your Coolant Reservoir tank is not failing. In my case had a "coolant low" warning light. Checking the reservoir it showed to be normal level. Decided to replace the coolant level sensor thinking it to be faulty. Coolant low still came up after this change, so replace the coolant reservoir tank with a new one. Turned out to be the float in the tank losing it's "buoyancy" and sinking to the bottom of the tank giving a low read.

 

As Nansan says, the coolant low warning comes from the float in the expansion tank. The float is known to lose its buoyancy and sink even when there is sufficient coolant so first check that its floating, you can see if you remove the expansion tank cap. It will also not float if the water/coolant mix isn't the correct density, so if your 50/50 mix isn't right it might not float. If it is floating the sensor maybe faulty, or there is a wiring fault to the sensor.

If the engine is too hot it will warn you and put you in "restricted performance" mode, it won't give you a low coolant warning unless its getting that from the sensor (or lack of sensor)

 

Thanks for the input Nansan21 and fivel.

 

I looked inside the coolant expansion tank with a flashlight and I couldn't see anything because the coolant was kind of cloudy and not clear. So, I poked inside with a small coffee stirring stick (wooden) and I couldn't feel anything. If there's a float, I couldn't find it.

 

It really doesn't matter. The sensor is bad and even if there was a way to replace the sensor without replacing the tank, by the time the sensor is bad the tank needs to be replaced anyway. A replacement tank comes with a new sensor. They are a wear item on cars made these days lasting only a few years.

Replace the coolant tank.

 

I found the expansion tank for my car (part no.C2C41899). It lists for $143 (discounted price of $86). Is it relatively easy to replace without a lift and without draining tall of the coolant?

 

Deleted due to duplicate post.

 

 

I got an aftermarket expansion tank for only $60 and installed it myself based on the video in this thread. I still have the low coolant fluid light. What should I do now?

 

Problem solved. I took the car to my local mechanic who knows me and he said the bottom hose to the expnsion tank wasn't all the way in and was leaking. He re-attached it and the indicator went away. He didn't even charge me anything. All's well that ends well.