2000 s70 bad coolant sensor?

Gatekeeper21 · Post by **Gatekeeper21** » 13 Jan 2011, 17:51

So, my low coolant light came on today on they way home from work. I checked the level in the overflow tank and it was only about a half inch below the max level. I added a little water just to get it up to the line. When I initially start the car, the light was off. As soon as I give it some gas, the light comes back on and stays on. I have double checked the connection of the sensor and it is good. I was initially scared there was a clog, but the hose from the engine to the radiator is quite hot, so that changed my mind. Is this just a bad sensor that needs to be replaced? Are there any fuses or anything else I should check before replacing the sensor? Any help would be appreciated.

Also, if it is the sensor, is this something I shouldn't drive the car without fixing or is it something that can go a few days until i have a chance for one to be delivered from fcpgroton and just keep constant watch on the temp?

Post by **jimmy57** » 13 Jan 2011, 18:06

The sensor is a simple magnetically triggered switch and is very reliable but they can fail.
The sensor is trigered by a float with a magnetic washer in it that is circular and floats up and down on a hollow part of the tank. The sensor inserts from below into the hollow area.
The float may not be floating is another possibility.
Take off cap and look forward and down and you should see the float, it is white. If it is floating at the top of the coolant level then sensor is likely the problem. IF you get a piece of wire there is a slot next to float area that will allow you to hook and lift the float. If it bad it will sink down again. The washer level sensor is the same type system and they sink sometimes too as well as sensors failing.
You should recheck to be sure the coolant level didn't go down again when you ran engine before you do anything else. If the coolant level dropped again because of some trapped air that purged then there is nothing wrong and you just need to add coolant.

Post by **Ozark Lee** » 13 Jan 2011, 19:04

If the coolant level is still OK yet you still have the light take the palm of your hand and smack the coolant overflow tank. The float can get stuck and that can often pop it free. If that works you should still eye a replacement float switch soon since the problem tends to get worse with time.

...Lee

FCPEURO · Post by **FCPEURO** » 13 Jan 2011, 20:15

+1

Had the same issue back in the day with my XC70. To bad I did not replace it and ended up overheating the car because I did not know I was loosing coolant. Just make sure you replace the sensor if it is bad soon.

Gatekeeper21 · Post by **Gatekeeper21** » 15 Jan 2011, 07:56

Thought I posted a reply the other night, but it obviously didn't show up. I couldn't see the sensor, so i poked at it with a screw driver and spun it around (before i saw your post ozark). The light did not come on at all yesterday, so that seemed to take care of it. If it starts acting up again in the near future, I will make sure to replace it. Thanks for all the info