Low coolant light on again

BIGDL1981

MEMBER
2000 MERCURY SABLE
6 CYL
2WD
AUTOMATIC
120,049 MILES

3.0 DOHC, I flushed the coolant about a month ago (very dirty changed out the hoses and installed a new thermostat. When I filled it back up the low coolant light stayed on. I figured it was the sensor in the coolant tank so I bought a replacement Dorman tank and installed it. The problem seemed to go away for a couple of weeks, car was fine and warmed up as it should. Now the low coolant light is back on, coolant level is perfect but the car seems to take forever to warm up. Possible bad thermostat after 2 weeks? Would that throw off the low coolant sensor in the tank though? Any suggestions would be appreciated.

1 Reply

WENDY W

MECHANIC
86 POSTS

Hello!

Perhaps the connector plug is not making a good connection with the low coolant sensor. You may want to check for any corrosion on the contacts of the connector plug and ensure that the connector plug is fully seated on the sensor.

The thermostat that the manufacturer recommends for this vehicle is designed to begin opening at 175 degrees (Fahrenheit) and is fully open at 210 degrees. You may want to check that you received the correct thermostat. If the thermostat opens prematurely, or if it was installed facing the wrong direction, it could prevent the vehicle from coming up to the appropriate operating temperature. The following video tutorial has some helpful tips on replacing a thermostat:

https://youtu.be/EZ4luHCzBeo

There's also a possibility that the engine temperature sensor is faulty or making a poor connection at the wiring harness, which could cause it to send an incorrect reading to the vehicle's power control module. These repair guides go into more detail:

https://www.2carpros.com/articles/symptoms-of-a-bad-coolant-temperature-sensor

https://www.2carpros.com/articles/engine-cooling-system

Please check out the diagrams (below) and let us know what you find.

Thanks! Wendy W

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