Question about 1999 Pontiac Montana

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Bad low coolant sensor on side of radiator

Do you have to drain any coolant from radiator to replace it? I never have replaced one before. I am just not sure how to R/R sensor.

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  • Anonymous Mar 17, 2009

    Bad low coolant sensor.



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If you are replaceing the coolant sensor make sure the car is cool and the coolant lost is very small and be sure to put some telfon tape on the threads before installing

Posted on Feb 01, 2009


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The low coolant light keeps going off have had the radiator replaced and it doesn't get hot but the low coolant light still goes off

There is a switch (sensor) that is installed in the radiator tank, partway down one side that monitors coolant level. It would not be included with a new radiator, so if it was not replaced when the radiator was done, chances are that the sensor was just moved from one to the other. The sensor is probably going bad. You were right about the A/C. It has nothing to do with this issue. It is not a critical sensor, but light can be annoying. If you replace it, chances are your problem will go away. If you wish, you can disconnect the electrical cable from the sensor. If the low coolant light is then lit, you can ground the sensor cable to make it go out. If it goes out with the cable removed, then you can just tie it back. Just remember, though, that you no longer have a low coolant detection capability. Regular checks of the coolant level would be required, although this should be normal procedure anyway.

Nov 23, 2015 | 1986 Oldsmobile Delta 88

1 Answer

The low coolant light is continually on in my 1998 Buick Regal. The people at Jiffy lube tell me not to worry about it. I brought it to a mechanic today and they thought the sensor needed to be replaced....

Hello: The low coolant light sensor is in the radiator tank on the passenger side. Sometimes you can take a small hammer and tap on the radiator tank next to the to the sensor. THIS HAS WORKED FOR ME SEVERAL TIMES. IF YOU HAVE TO REPLACE THE SENSOR ITS NOT THAT BIG OF JOB. You will have to drain the radiator below the sensor level. There should be a drain **** on the bottom of the tank on the drivers side. Hope this helps.

Apr 07, 2011 | 1998 Buick Regal

2 Answers

Coolant level sensor

this is a common problem and there is a factory service bulletin about it, just replace the sensor, it is located in the plastic side tank of the radiator and held in by a spring clip.

May 12, 2010 | 2000 Buick LeSabre

2 Answers

How do you reset the low radiator fluid light on the dash? Fluid res. was low. I re filled but lite won't go out.

There is no reset button.When you fill it up it should just go out.What happens is the sensor is at the bottom of the fill bottle and all the dirt and junk is at the bottom.Sometimes the sensor is on the radiator.It is directly below filler neck of the radiator.Drain enough coolant to lower the level of the radiator and remove the metal retainer from the sensor.Remove the sensor and install a new one in.Refill the radiator.The light should be off.Make sure the vehicle is cooled down when working on the cooling system.

Nov 24, 2009 | 1997 Pontiac Grand Prix

2 Answers

Where is the thermostat sensor

Both the 4.0L and 4.7L engines use 195� thermostats for all model years from 1999-2004. When replacing a thermostat it is very important to install one with the same temperature rating (the only exception might be with certain performance modifications or chips that recommend or require a different temperature thermostat).


1. DO NOT remove radiator cap first. With engine cold, locate radiator draincock on the right lower side of radiator facing to rear of vehicle.
2. Attach one end of a hose to the draincock. Put the other end into a clean container. Open draincock and drain coolant from radiator. This will empty the coolant reserve/overflow tank. The coolant does not have to be removed from the tank unless the system is being refilled with a fresh mixture. When tank is empty, remove radiator cap and continue draining cooling system. To drain the engine block of coolant, remove the cylinder block drain plug, located on the side of cylinder block below the exhaust manifold.

4.0L engine - refilling the cooling system Coolant recommendations and cautions: The recommended mixture is 50/50 ethylene-glycol and low mineral content water. Never use pure antifreeze. Only Mopar Antifreeze Coolant, 5 Year/100,000 Mile Formula (glycol base coolant with corrosion inhibitors called HOAT) is recommended. This coolant offers the best engine cooling without corrosion when mixed with 50% distilled water. Antifreeze mixture must always be at least 44%, all climates year round. Maximum protection (-90d) is provided with a 68% mixture protection. If the percentage is lower than 44 percent, engine parts may be eroded by cavitation, and cooling system components may be severely damaged by corrosion. CAUTION: Mopar Antifreeze/Coolant, 5 Year/100,000 Mile Formula (MS-9769) may not be mixed with any other type of antifreeze. Mixing of coolants other than specified (non-HOAT or other HOAT), may result in engine damage that may not be covered under the new vehicle warranty, and decreased corrosion protection.

CAUTION: Do not use coolant additives that are claimed to improve engine cooling. 4.0L coolant capacity: 1999-2000: 13.0 qts. (including 2.3 qts. for resevoir) 2001-2004: 15.0 qts. (including 1 qt. for resevoir)

1. Tighten the radiator draincock and the cylinder block drain plug(s) (if removed).
2. Fill system using a 50/50 mixture of ethyleneglycol antifreeze and low mineral content water. Fill radiator to top and install radiator cap. Add sufficient coolant to the reserve/overflow tank to raise level to FULL mark.
3. With heater control unit in the HEAT position, operate engine with radiator cap in place.
4. After engine has reached normal operating temperature, shut engine off and allow it to cool. When engine is cooling down, coolant will be drawn into the radiator from the reserve/overflow tank.
5. Add coolant to reserve/overflow tank as necessary. Only add coolant to the reserve/overflow tank when the engine is cold. Coolant level in a warm engine will be higher due to thermal expansion. To purge the cooling system of all air, this heat up/cool down cycle (adding coolant to cold engine) must be performed three times. Add necessary coolant to raise tank level to the FULL mark after each cool down period.

For more details, you can refer to the Jeep WJ Service Manual Section-07-Cooling-System-Ewj7

Hope helped.

Nov 02, 2009 | 1999 Jeep Grand Cherokee

1 Answer

Replace coolant level sensor


Jul 17, 2009 | 2000 Oldsmobile Silhouette

2 Answers

The low coolant level light keeps coming on on my 1995 camaro z28. I have replaced the radiator, thermostat, and coolant level sensor. That I know of, there are no leaks. What do I do?

Replace the low coolant sensor right side if radiator. When you replaced the radiator
they may have installed the old sensor.

I had the same problem.


May 02, 2009 | 1995 Chevrolet Camaro

1 Answer

Radiator Electric Fan Motor on a 2003 Buick Century won't come on when temp gets high

I have a 1997 Buick Century with the same problem. Both my fans work if the A/C is
on as they should. If your turn off the A/C the passanger side fan will not come on
and at an idle the coolant in the radiator will boil, you can hear it in the overflow tank.
If you are driving there is enough air flow thru the radiator that the coolant doesn't
boil and the car doesn't overheat. I have replace the water pump, the thermostat.
and the ETS or engine temperature sensor mounted just above the thermostat in
the thernostat housing, to no avail, I still have the same problem. The only other
thing is the coolant level sensor in the radiator, which I haven't replace yet due
to the fact you have to pull the radiator in order to replace it, which is a major
undertaking. I have a low coolant indicator on all the time on the dash so I have
a pretty good idea the coolanat level sensor is bad. The coolant level is not low
so that sensor is not working as it should. I hope this may help with your problem.
To test you fan raise the hood when it is cold and top off the radiator and fill the
overflow tank to the cold mark. Start the car and let it idle with the A/C off and
see if the drivers side fans comes on. It will have to get to operating temp
before the fan will come on. If it doesn't come on replace the radiator low coolant
sensor on the passanger side of the radiator. If that doesn't fix the problem
replace the thermostat and the Engine Temperature Sensor at the thermostat
housing with an A/C Delco Engine Temperature Sensor. Good Luck..

Sep 26, 2008 | 2001 Buick Century

1 Answer

Intermittant low coolant light. Have flushed system, replaced low coolant sensor

The coolant sensor located in the radiator is either gunked up or faulty if the fluid level stays ok.. The sensor is located on the engine side of the radiator about 3 inches from the top on the right side looking from behind the steering wheel

Jul 19, 2008 | 2002 Chevrolet Impala

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