Low Temp light on, Coolant OK
Low Temp light on, Coolant OK Last week my low coolant light started coming on intermittently after the car had warmed up a bit. Now it stays on as long as the car is on and at normal operating temp, about 210. I checked the fluid level its good, the car isnt overheating, and there is no smoke of any kind coming from the exhaust. I cannot find any leaks in the system either. My brother, who is a tech at BMW of Dallas, was telling how the coolant level sensor worked, and basically it is a metal peice that is grounded by a current that is carried through the coolant. When the ground is lost, b/c of low coolant, it throughs a light. So, the two possibilities I can think of at the moment is
1. the coolant is past its prime ( I am flushing the radiator next week).
2. The sensor is bad, or broken.
The car has 127k on the odometer, So I am sure it has todo with a fatigue of some sort. Has this happened to anyone else? While I have the radiator drained I was gonna check the coolant level sensor, but I don't know where it is.
Any help out there?
Thanks,
Josh
1. the coolant is past its prime ( I am flushing the radiator next week).
2. The sensor is bad, or broken.
The car has 127k on the odometer, So I am sure it has todo with a fatigue of some sort. Has this happened to anyone else? While I have the radiator drained I was gonna check the coolant level sensor, but I don't know where it is.
Any help out there?
Thanks,
Josh
TECH Senior Member
Joined: Dec 2001
Posts: 5,399
Likes: 3
From: Jacksonville, FL
The sensors do go bad. While you have the radiator drained take it out and clean it - sometimes that'll work. If it doesn't you can get a new one, or just unplug the sensor and that will keep the light off permanently. The sensor is located about 4-5" below the radiator cap, has a connector with 2 wires I believe. I'd just unplug it, my car didn't even come with one.
Originally Posted by 2001NBMZ28
The sensors do go bad. While you have the radiator drained take it out and clean it - sometimes that'll work. If it doesn't you can get a new one, or just unplug the sensor and that will keep the light off permanently. The sensor is located about 4-5" below the radiator cap, has a connector with 2 wires I believe. I'd just unplug it, my car didn't even come with one.
is your coolant "oily"? my sensor got contaminated by power steering fluid. cleaning the sensor and reinstalling it fixed it, but the power steering fluid contamination was caused by the "power steering cooler". it is a metal pipe in the middle of the upper radiator hose. it has power steering fluid lines running to it, as well as the coolant running through it. in my case the "cooler" allowed the power steering fluid to leak into the coolant and one of the results was causing the coolant level sensor to malfunction. rapidly losing my power steering fluid was a worse problem. replacing the "power steering cooler" and flushing/filling the PS and radiator fixed the problem.
the test for this condition is to get a radiator pressure tester (free loan from autozone) and pressurize the cooling system, then look for air bubbles to appear in the PS resevoir. I had never heard of this happening before mine, but a few others have read my previous posts on this and discovered they had the same problem. mine is a 98, not sure if the later ones have the same "PS cooler" setup. Mine was a minor, on-going problem until the internal leak got bad enough to cause very rapid lose of PS fluid. like anything else- when it gets bad enough its easy to find the problem.
the test for this condition is to get a radiator pressure tester (free loan from autozone) and pressurize the cooling system, then look for air bubbles to appear in the PS resevoir. I had never heard of this happening before mine, but a few others have read my previous posts on this and discovered they had the same problem. mine is a 98, not sure if the later ones have the same "PS cooler" setup. Mine was a minor, on-going problem until the internal leak got bad enough to cause very rapid lose of PS fluid. like anything else- when it gets bad enough its easy to find the problem.
I have a regular TA so no PS cooler for me. The coolant looks fine, and there is no leaks when the system is pressurized. The thing is I probably need to just flush the whole thing out, I will probably do that tomorrow, and I will check the sensor and either replace or clean it.
Josh
Josh
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Teching In
Joined: Mar 2006
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On My Third Sensor I'm on my 3rd low coolant sensor in my '99 SS with about 57K miles. Around 15K the light started coming on intermittently. I'm pretty good about checking/changing my fluids, so I was not surprised when I double checked and found no obvious problem. Under warranty, I took it in, and the dealer seemed none too surprised that the sensor was bad. I asked for details, and got a bit of a run around. However, I made sure they changed the fluid and checked everything out. 15K miles later, I was back at the dealership (light came on and stayed on this time). Now I'm pissed for wasting my time and with a little prodding get the guys to admit that it is a regular problem. I'm not sure if yours is the same sensor, but bad sensor would be my first guess.
Later I read that it was one of the highest warranty items (can't back it up with numbers, but that's what I recall one article stated). Anyway, I have had no problems since, and it is the only thing I ever took the vehicle in for regarding warranty.
Later I read that it was one of the highest warranty items (can't back it up with numbers, but that's what I recall one article stated). Anyway, I have had no problems since, and it is the only thing I ever took the vehicle in for regarding warranty.
