coolant level sensor

[hrtfxr]

Just replaced my cooling system (Aluminum T-stat housing, radiator, water pump pulley) as well as water pump, t-stat, coolant reservoir and cap. Fan delete, too. Replaced the coolant sensor, as well. I have a small leak around the cap somewhere. What is really bothering me is that the coolant level sensor is coming on at start up and shut down with plenty of coolant in the reservoir. I never have added more than 2 oz to it.
Why is this sensor firing off?

[bluptgm3]

What brand of parts did you use?


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[hrtfxr]

I don't know, why?

[bluptgm3]

Sometimes inferior parts do not work well.


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[BMWManiac]

I bought a knock off from FCP for $10....failed upon install. Go with a OEM one. Before you drain the coolant to install, unplug the currently installed sensor, plug in your new sensor, hang it upside down, and go and turn your car on....

This is a simple switch. If the float is at the top, there is no error message. You'll hear people post about the tank or whatever....it is all in this sensor. Now, it is possible that you still need to bleed the system. Sometimes the fluid level drops and will stay low....you need to keep bleeding until you get all the air. It usually takes me a while to do this over the course of a couple weeks.

[hrtfxr]

I bought a knock off from FCP for $10....failed upon install. Go with a OEM one. Before you drain the coolant to install, unplug the currently installed sensor, plug in your new sensor, hang it upside down, and go and turn your car on....

This is a simple switch. If the float is at the top, there is no error message. You'll hear people post about the tank or whatever....it is all in this sensor. Now, it is possible that you still need to bleed the system. Sometimes the fluid level drops and will stay low....you need to keep bleeding until you get all the air. It usually takes me a while to do this over the course of a couple weeks.

Bought at autozone after the one from the Import Parts Depot "failed". That one came along with reservoir and cap.
9Seems unlikely that both fail new. I have bled several times. I will again.
It is not always showing the message.
Anyway, I will try the test on the first one.
Thanks

[Thresher]

Just replaced my cooling system (Aluminum T-stat housing, radiator, water pump pulley) as well as water pump, t-stat, coolant reservoir and cap. Fan delete, too. Replaced the coolant sensor, as well. I have a small leak around the cap somewhere. What is really bothering me is that the coolant level sensor is coming on at start up and shut down with plenty of coolant in the reservoir. I never have added more than 2 oz to it.
Why is this sensor firing off?

Check the connector that mates up with the coolant level sensor. I just had mine replaced; the electrical connection was failing and there was arcing. There is a newer version of the connector that is shorter. Funny; I guess "newer" is relative these days.... my car is a 1996 and I believe my mechanic said the newer style was found in 1998+.

[JDStrickland]

The Low Coolant Sensor is nothing more than a reed switch with a magnet that passes nearby. I believe the switch closes when the float (magnet) drops. A false low would mean that the switch contacts are closed even though the magnet is up. In any case, you need to troubleshoot the Low Coolant sensor, I think you are getting a short (ground) at all times.

[E30DEE]

I’ve recently had similar issues in my car and replacing this fixed the problem https://amzn.to/2W7Hj2w

[hrtfxr]

I did replace thie sensor, twice, and the problem persists. Not much lately. I am thinking of replacing the wiring and connector.

[BMWManiac]

I did replace thie sensor, twice, and the problem persists. Not much lately. I am thinking of replacing the wiring and connector.

When you say, not much lately, are you saying that sometimes the error pops up and sometimes it doesn't?

The next time it comes on, pop your hood, and shine a flashlight at the side of the expansion tank and see if the fluid is below the float. As I've said before, sometimes if not bled enough, you will notice that the coolant level will be low. As soon as you crack open the system, the fluid level will rise to normal and you'll think the sensor is bad.....

[Eric93se]

I also think this might be air in the system. But two things, you've driven it a lot and you've replace the expansion tank. Try adding another inch or two of coolant.