low coolant level sensor - Maintenance and Repair Forum

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low coolant level sensor
Saturday, May 05, 2012 7:33 PM
My low coolant light is on despite the fact that the there's plenty of coolant and when I unplug it, the light goes out. So I'm gonna replace the sensor and I was wondering if the sensor just pulls out of the overflow tank.

Re: low coolant level sensor
Saturday, May 05, 2012 9:30 PM
mine did that for a while..i just went and bought another tank for 7 bucks at the local junkyard...



Re: low coolant level sensor
Saturday, May 05, 2012 9:40 PM
Give it a whack.





Re: low coolant level sensor
Wednesday, May 09, 2012 9:15 PM
sensor bad

new one


-96 cavalier 2.2 auto 143k miles
Re: low coolant level sensor
Wednesday, January 28, 2015 3:14 PM
The sensor is located on the outside of the tank. It is easy and cheap to remove (with a needle-nose pliers) and replace, but I think in most cases (definitely in my case) the sensor is not the problem. The problem is that inside the reservoir tank (near the sensor) there's a bobber that should float up and down with the coolant level, but sometimes the bobber gets stuck at the bottom of its track. The bobber contains a magnet which the sensor detects across the reservoir tank wall. If the bobber is stuck at the bottom, the sensor detects it and so the sensor reports that the coolant level is low.

I assume that the bobber is usually the problem because my mechanic immediately told me that I needed to replace the coolant reservoir-- and he told me that I could easily do so myself. He didn't tell me to replace the sensor. He knows his stuff. But I still thought I'd try replacing the sensor. I replaced the sensor but it didn't help. He was right.

If the problem is a stuck-bobber, then you can try to fix it in one of 3 ways:
1) Try tapping the reservoir (near the sensor) with a hammer and/or screwdriver butt firmly to jar loose the bobber-- but not so hard that you crack the reservoir tank. This worked for me one time but then it got stuck again about a year later and I couldn't jar it loose.
2) Empty and remove the reservoir tank. Then hold it upside down and tap it against a hard surface in order to jar the bobber loose. If the bobber can move freely, you'll hear it knock back and forth when you shake the reservoir tank. If the bobber is stuck, you won't hear it knock back and forth. If you try this method, I'd also recommend that you flush it with clean water several times (perhaps blasting it with a garden hose also) and shaking it back and forth so that the bobber is good and loose, and that any sediment and other problem-causing gunk is removed.
3) Replace the coolant reservoir tank. They are about $45 on Amazon as of January, 2015.

FYI: Removing the reservoir is pretty easy.
1) Drain the coolant reservoir with a turkey baster.
2) Use a pliers to pinch and slide-away the hose clamps.
3) Pull off the hoses. (They may be stuck
3) Remove the sensor connector.
4) Unbolt the reservoir. If I remember correctly, it's held in by one 10mm hex-head screw at the front.
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