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My add coolant light comes on although the reservoir is full

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The low coolant sensor could be stuck...this is located sometimes in the bottom of the overflow tank...(a light tap can sometimes correct) or some are located on the radiator...follow the electrical long as coolant is circulating properly...this is probably the culprit...if the sensor is on the radiator...a light tap applies can disconnect periodically as this sometimes can correct...Hope this helps.

Posted on Apr 01, 2011


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I have a 1999 chevy camaro and I need to add coolant. do I add coolant to resevoir only or to radiator only or to both?

If the engine is cool, what you should do is open the radiator cap and top off the coolant in the radiator. Then, fill the reservoir to slightly above the Full Cold level. This will allow for some additional coolant to enter the system since it will probably need more than what you put in the radiator. After that, as long as you keep the reservoir level between the full cold and full hot levels, you should not have to add any additional coolant to the radiator itself.

Dec 07, 2015 | 1999 Chevrolet Camaro

1 Answer

My early wRning light for low radiator fluid comes on at the start turn on my ignition, but it goes away shortly after. I bought 50/50 and filled the coolant reservoir to the full line. But the light still...

The CHECK COOLANT indicator illuminates when the coolant level is low in the coolant recovery reservoir. The low coolant level switch is probably in or on the coolant reservoir !

Feb 19, 2015 | Cars & Trucks

1 Answer

Why would the coolant light keep coming on when it is full?

Is the reservoir full and radiator and if so check if theirs a sensor on the reservoir if there is a sensor possibly have to replace the reservoir or try and disconnect the sensor and see if light goes out just make sure you have no leaks.

Sep 21, 2014 | 2000 Ford Taurus

1 Answer

The radiator light is on and I wanted to know what that could mean.

You're probably low on coolant. Check the coolant reservoir under the hood, and if it's below the "Full" line, add coolant until it is full. If you're not familiar with the coolant reservoir, look in your owner's manual under "Cooling/AC system" or "Maintenance". There should be a picture or drawing of the reservoir along with instructions for filling it. Good luck.

Oct 01, 2013 | 2006 Saturn Vue

1 Answer

Why is my add coolant light on

your coolant light is on because there is not enough coolant in the radiator. When the coolant is hot it expands and the excess water is pushed out into the reservoir and as it cools down the water is sucked back in and so keeps the top tank of the radiator full. However if you have a leak or a faulty radiator cap the water comes out ok but instead of sucking back in water it allows air in instead. Therefore you have a one way circuit of water out but no water back in. Your coolant light is telling you to check out the fault before you over heat the engine

Jul 15, 2013 | Cars & Trucks

1 Answer

Why is my add coolant light on ?

Check the level in the radiagtor, and you may have a small leak.
Launch X431

Jul 15, 2013 | 1999 Mercury Cougar

1 Answer

Where do I add antifreeze

if you dont see radiator cap on pour coolant in the coolant reservoir jug until coolant level stay on full cold mark.when adding coolant to coolant reservoir jug when coolant level stop dropping stay at full cold have correct amount antifreeze in radiator.

Mar 26, 2013 | Cars & Trucks

1 Answer

I have a 2003 VW Passat 1.8T. When I first start and drive the car, the coolant temp is normal. After a few miles, it will suddenly climb to the red, and STOP check coolant comes on. If I loosen the cap to...

Has coolant level been going down in return reservoir at all, as in have you had to add coolant recently to bring it up to top level? Have you tried running engine from cold, with heater on and let it run up to normal temperature with cap off return reservoir? If not do so, and watch level in reservoir and if it goes down, add as needed until engine running at normal, and not overheating. Allow rad fan to kick on & off a few times before re-installing cap on reservoir. Pay close attention to engine temp while doing this. If it goes high, shut it off and let cool. Be careful, my son's Passat just had overheat problem and turned out to be impeller on water pump ( internally) was spinning on shaft of pump. Thermostat is certainly a consideration if coolant is full, and all air bled out. Keep me posted on what happens when you run with cap off and keep reservoir full. Don't forget, heater on while doing this.

Dec 05, 2012 | Cars & Trucks

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Coolant Light is on even when its to the full line, not overheating but i am loosing coolant overnight and have to replace it

You say "when it's to the full line". If you are referring to the plastic coolant reservoir, that is not an indication of how much coolant is in the radiator. You must remove the radiator cap to check the coolant level and too add coolant. If you are pouring coolant into the reservoir, and the radiator is low, then the coolant in the reservoir is probably being pulled into the radiator after you have driven the vehicle. That doesn't mean you are losing antifreeze. It just means you need to put antifreeze in the radiator.

Jan 02, 2011 | Chevrolet Cavalier Cars & Trucks

1 Answer

I have a 1992 Buick Regal, and my coolant light was on the other day, and after I added some fluid to the overflow tank, it is still on. How do I add the coolant to the radiator itself? because I think...

3.1 liter?

If so the level sensor is in the reservoir. Sometimes the level gets stuck if the coolant gets low. Some gentle whacking of the reservoir with a rubber mallet is usually enough to get the light to turn out.

3.8 liter?

When the car is cold remove the radiator cap on the passenger side of the radiator. Add coolant until full.

I’m happy to assist further over the phone at

Nov 04, 2010 | 1992 Buick Regal

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