1999 S80 T6 Low Coolant Level Sensor Problems

Jmast755 · Post by **Jmast755** » 06 Apr 2015, 13:13

I recently replaced the timing belt and the water pump in my car after a bad coolant leak. I also replaced the expansion tank and level sensor. I am getting the errors "Low Coolant Level" and "Low Coolant shut engine off ASAP" messages even though my tank is full. There are no leaks and my coolant sensor/expansion tank is brand spanking new. Also, the cars temperature does not exceed the middle point or the normal temperature zone. Does anyone know what else could be triggering this problem? I'm baffled and I can't stand looking at this message every day. Please help!

THAI UNG · Post by **THAI UNG** » 06 Apr 2015, 19:51

I think the float inside your expansion tank is stuck just like mine a year ago ( My lower price after market expansion tank). I used a small stick aprox.6" long to push down and pull up the float several times to prime it and it worked,no more "Low Coolant" message. Make sure before you work on it ,the engine is cold,the coolant sensor click into the exp.tank and the plug connector is connected.Hope this helps...

Jmast755 · Post by **Jmast755** » 07 Apr 2015, 11:37

Thanks for the response. I used a pair of tongs to pull up on the float and got the light to turn off but then it went back on once I released the float. Not sure if the float is actually "floating" or not. I contacted the after market dealer and they are sending me a new tank for free. I will try your method and try to get the float to loosen it up and see what happens. If not i'll just replace the new tank with the "new new" tank.

Cees Klumper · Post by **Cees Klumper** » 07 Apr 2015, 21:19

Sounds like a sensor / sensor wiring problem. Even though it's new, I would try a different one, that should remedy it.
I had a similar problem, after I replaced my expansion tank the sensor started malfunctioning. Replaced with new and problem was solved.

Post by **precopster** » 08 Apr 2015, 04:01

There is a burr in the float area of the expansion tank stopping the float from moving freely. The sensor is a simple circuit with 12V going in at one end of the connector. Test the connector for voltage.

Jmast755 · Post by **Jmast755** » 08 Apr 2015, 11:53

The float is not "floating" at all. I can't push down on it with a screw driver because it is already down all the way (as if no liquid is in the tank which is not the case). Only when I pull up on it does the light in my car go off and then when I let go the light turns back on.

Watch this video. I left my phone recording while I lift up the float in my car. FF to 48s in and you'll see what I am talking about.

THAI UNG · Post by **THAI UNG** » 10 Apr 2015, 12:02

The float will not floating when coolant at or below MIN.line,and it will( under coolant surface level)when coolant at or a bit below MAX.line,it cans travel up and down less than 3/4".If your coolant is full and still not floating then you have a defected float.Btw cut a wire coat hanger approx.6-7"long and bend small a L shape on one end,so you can use it to push down and pull the float up a bit easier...

Post by **abdomar528** » 12 Mar 2016, 21:16

Hi All, check this video out I made:

Even though the float may go all the way up, the mechanism might be bad. I tested a bad tank (new one) with another coolant tank I bought. I compared the two in the video and found that the first new tank I bought was defective. Watch the vid and see how I tested to see if the tanks float mechanism is bad.

Thanks!

loveMy850 · Post by **loveMy850** » 10 Mar 2019, 09:01

Ok where's the float in the reservoir tank? Thanks

Post by **precopster** » 10 Mar 2019, 17:02

loveMy850 wrote: ↑10 Mar 2019, 09:01 Ok where's the float in the reservoir tank? Thanks

Remove the cap and look down. That round object is the float.