faulty low coolant sensor?
Thread Starter
Joined: May 2006
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From: somewhere that doesn't get snow
faulty low coolant sensor? Got in my car this morning and the low coolant light came on. Checked the radiator and it was full added some coolant and filtered water to the overflow just in case and its still on. I didnt see any coolant leaking out.
Thread Starter
Joined: May 2006
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From: somewhere that doesn't get snow
i think i found the problem. the coolant overflow cap may not have been secured properly and after topping it off (which i don't think it needed any) i just put the cap back on. while getting a car wash this morning i was reading shboxes site about how if the cap isn't secured properly to the overflow tank it can trip the light. i went home and made sure the cap was secure, which it wasn't so i made it tight and started the car and no more light! 
Common problem that the sensors go bad. Either replace it or simply uplug it to get rid of the light. I unplugged mine and never looked back. I routinely check my levels so i never have to worry about it.
TECH Veteran
Joined: Dec 2008
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From: Little Rock, AR
i think i found the problem. the coolant overflow cap may not have been secured properly and after topping it off (which i don't think it needed any) i just put the cap back on. while getting a car wash this morning i was reading shboxes site about how if the cap isn't secured properly to the overflow tank it can trip the light. i went home and made sure the cap was secure, which it wasn't so i made it tight and started the car and no more light!
The cap only keeps the coolant from sloshing out and gives a place for the level indicator. It is not pressurized on the f-body. The low coolant light can be a common come and go issue. Thread Starter
Joined: May 2006
Posts: 3,452
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From: somewhere that doesn't get snow
maybe i misread it and thought thats what it said, but the truth is, it was on constantly including to and from the car wash. once i got in the garage the only thing i did was pop the hood and play with the cap and make sure it was tight. then the light went off. i can't explain it but that's how it happened.
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Verdad Gallardo Thread Starter
Joined: May 2006
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From: somewhere that doesn't get snow
it would come on when the ignition went on and never go off. now it comes on when the ignition comes on and shuts off like normal. i did smell a little coolant under the hood but that was after i added some with a makeshift paper plate funnel and even though i didn't spill any there might have been a drop or 2 land in the engine compartment when i pulled the plate out so i probably was smelling new stuff. there was nothing on the ground so i don't think it's leaking anywhere.
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Joined: Jan 2013
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From: Thibodaux LA
i had the same problem. the coolant light would come on when it would get to bout 175 every time. it would never go over 180. I would check the radiator cap and it would be full. after searching and read that the sensor goes bad, i just unplugged it.
Thread Starter
Joined: May 2006
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From: somewhere that doesn't get snow
Came on again tonight intermittantly. Seems like sometimes it wont shut off after key on test and other times it goes off normally.
does the light coming on when the car is cold and full of coolant at the radiator indicate a faulty sensor? if i turn the key off and on a few times i can get the light to go off sometimes. other times it comes on and stays on. this is all with the engine off. seems like there is a coolant hose jammed right up against the sensor so i can't even unplug it. maybe if i remove the battery i'd have more room. i hope i don't have to drain coolant just to replace that sensor.
does the light coming on when the car is cold and full of coolant at the radiator indicate a faulty sensor? if i turn the key off and on a few times i can get the light to go off sometimes. other times it comes on and stays on. this is all with the engine off. seems like there is a coolant hose jammed right up against the sensor so i can't even unplug it. maybe if i remove the battery i'd have more room. i hope i don't have to drain coolant just to replace that sensor.
Last edited by 1995blacktattop; Apr 27, 2013 at 11:37 PM.
Thread Starter
Joined: May 2006
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From: somewhere that doesn't get snow
well i went and got a new sensor and some coolant and a syphon to try to get enough coolant out of the radiator to get the sensor out. well i got some out but apparently not enough cause as soon as i took the sensor out coolant started pouring out onto my garage floor.
i got the new sensor in and coolant in and battery back in and turned on the ignition only to find i had no coolant light whatsoever. not even during the test period like the bad sensor
so i pulled the car out of the garage removed the battery and proceeded to dump more coolant on the ground as i put the old sensor back in (after trying to clean it)
i thought that worked except after 2-3 tests the low coolant light stayed on solid again like it had been doing so i said **** it and just unplugged it. luckily i was able to get my $54 back on the stupid defective sensor.
why the hell is one small sensor so damn expensive anyway?
i got the new sensor in and coolant in and battery back in and turned on the ignition only to find i had no coolant light whatsoever. not even during the test period like the bad sensor
so i pulled the car out of the garage removed the battery and proceeded to dump more coolant on the ground as i put the old sensor back in (after trying to clean it)
i thought that worked except after 2-3 tests the low coolant light stayed on solid again like it had been doing so i said **** it and just unplugged it. luckily i was able to get my $54 back on the stupid defective sensor.
why the hell is one small sensor so damn expensive anyway?
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Joined: Apr 2013
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well i went and got a new sensor and some coolant and a syphon to try to get enough coolant out of the radiator to get the sensor out. well i got some out but apparently not enough cause as soon as i took the sensor out coolant started pouring out onto my garage floor.
i got the new sensor in and coolant in and battery back in and turned on the ignition only to find i had no coolant light whatsoever. not even during the test period like the bad sensor
so i pulled the car out of the garage removed the battery and proceeded to dump more coolant on the ground as i put the old sensor back in (after trying to clean it)
i thought that worked except after 2-3 tests the low coolant light stayed on solid again like it had been doing so i said **** it and just unplugged it. luckily i was able to get my $54 back on the stupid defective sensor.
why the hell is one small sensor so damn expensive anyway?
i got the new sensor in and coolant in and battery back in and turned on the ignition only to find i had no coolant light whatsoever. not even during the test period like the bad sensor
so i pulled the car out of the garage removed the battery and proceeded to dump more coolant on the ground as i put the old sensor back in (after trying to clean it)
i thought that worked except after 2-3 tests the low coolant light stayed on solid again like it had been doing so i said **** it and just unplugged it. luckily i was able to get my $54 back on the stupid defective sensor.
why the hell is one small sensor so damn expensive anyway?
I don't want to leave the thing unplugged but I can't stand driving around with any warning lights on, and I am not convinced that the sensor is bad, so what, a faulty plug?!
Could be if it's cheap Chinese crap. These sensors were notorious for going out years ago mostly because they would gunk up from the stop leak **** the factory used to put into the radiators. Some had luck just cleaning them where others just replaced and it worked fine. Mine went out a few years ago and haven't replaced it. Need to figure out how to jump the connector to keep it off.
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Joined: Apr 2013
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Also, I am not sure if the PCM reduces motor power to offset this sensor when it triggers the low-coolant warning light. I thought I read this somewhere on another forum. If so, it is all the more reason to unplug it and keep it unplugged. I am already getting much better at frequent fluid checks on my vehicle anyways.
TECH Veteran
Joined: Dec 2008
Posts: 4,147
Likes: 62
From: Little Rock, AR
