Low coolant light on

MARE222

MEMBER
2001 BUICK CENTURY
2WD
AUTOMATIC
82,000 MILES

My low coolant light comes on when I drive my car. My car does not run hot but the half way mark. I took it to Jiffy Lube the other day and they said since its hot outside they didn't want to chance the radiator spewing on them. They said they looked at my overflow and it was okay, but I didn't see them open it.
I have an appointment In 2 days and scared to drive my car for fear of overheating and breaking down on the highway. It is very hot where I live and going to be 95 degrees with a heat index of 105.
They seemed to think it was a bad sensor and said they couldn't check it because it was in the bottom of the radiator! Can I check my overflow safely and if it's low will it hurt to add water? I haven't changed my antifreeze in 3 years ( it was professionally done).
Jiffy Lube advertises they will top off or flush out radiator but when I got there they said they couldn't ( because it was hot outside). I just live 2 miles from the store and my car didn't have time to get hot. What can I do?

7 Replies

SCGRANTURISMO

MECHANIC
4,897 POSTS

Hello,

The overflow tank is where you add coolant to your vehicle;s cooling system. It is very easy to check. It will have two lines on it. The top line will be the hot mark. When your vehicle is at normal running temperature(hot) this is where your coolant level should read. The lower line will be the cold mark. When your vehicle has been sitting, say overnight, and is cold this is where your coolant level should be. Your low coolant sensor may be faulty. It is located on the right side of the radiator. If your temperature gauge never goes above the mid mark, I wouldn't worry to much about your low coolant light. The temperature gauge is the important gauge here. Your vehicle should be just fine to drive. Keep an eye on the temperature gauge and if your vehicle starts to get hot, pull over right away and turn it off and let it cool down. I think you will be just fine though, watch the temperature gauge, and replace the low coolant sensor when you can. Keep us informed as to what happens, please.

Thanks,
Alex
2CarPros

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Thursday, July 18th, 2019 AT 12:29 AM

MARE222

MEMBER
4 POSTS

Thank you. So if I check my overflow it should be full, but if not I need to add coolant? I wasn't certain if I needed to add that or water. I think I still have some Dex (?) From a few years ago when it was last checked. My temperature gauge goes to mid-range after I drive it a bit, but so far it doesn't go past the middle mark. Sounds like I'm safe unless the temperature gauge goes past the middle, correct?
Just this last week the low coolant light has came on (after I drive my car) and stayed. Before, it just blinked. Still a bit nervous to get on the highway. Just saying.

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Thursday, July 18th, 2019 AT 10:50 AM

SCGRANTURISMO

MECHANIC
4,897 POSTS

Hello,

Yes. If the temperature gauge stays in the middle you should fine. If you do need to add coolant, I recommend adding a 50/50 mix of coolant and water. This is how coolant usually is sold. Look at your coolant bottle to verify. What probably has happened here is one of the wires from your low coolant sensor has got a bare spot and has contacted another "hot" wire and created what is known as a short to power. This will illuminate your low coolant warning bulb in the dash. When the bulb was flickering on and off this is when the insulation was getting rubbed off and intermittently causing it come on and go off as contact was being made between the wires and then wasn't. Please keep us informed as to how things progress, and remember to keep an eye on your vehicle's temperature gauge until you get the short fixed.

Thanks,
Alex
2CarPros

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Friday, July 19th, 2019 AT 2:09 AM

MARE222

MEMBER
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Went to drop off my car today at an auto repair place I've gone to for a few years. They replaced the coolant, sensor and 1 of my belts. When they called to tell me it was ready to pick up, I asked them if they could check one of my tires that looked low. When I arrived they said when they did ( brought the car back in the garage) the low coolant light started blinking again! He said it might be the 'vehicle body control' whatever that is. They said it would take another day to check since it was closing time. They removed the new sensor and put the old one back in, saying that wasn't the problem.
He had mentioned an option before, which was to just unplug something or other so that I didn't have to see the low coolant light blink! I asked them to do it today ( for now) since that light drives me crazy! It cost me 283. Plus 26 in Lyft (transportation).
Did I do the right thing? At least I know now it's not the sensor, but I am still driving with caution.

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Monday, July 29th, 2019 AT 3:04 PM

SCGRANTURISMO

MECHANIC
4,897 POSTS

Hello again,

Absolutely. I believe they are referring to the Body Control Module (BCM), which could very well have an internal short to ground manifesting itself. We refer to these as "Gremlins" and they can be very hard to put a finger on sometimes. Please keep us informed as to how things progress. We are curious as to what the problem is as well.

Thanks,
Alex
2CarPros