Temp issues

Hey guys and gals. New day new problem. I recently did a coolant flush and filled it with g12 coolant. Since then, whenever I’m sitting still I get an overheat warning light, which isn’t to weird, it is north Carolina in August. The really weird part is that it will also kick the light when it starts. Doesn’t matter how long it sat or where. I park overnight in a garage, and it still goes off every morning. Once I drive about 2 or 3 minutes it goes away. Any ideas?

Do you have a scan tool? VCDS or and OBDII reader? Your car has two senors for water temps.

I’ve got a very cheap OBD2 sensor I’ll try it when I get home see if it gives me a read

My experience is: coolant light on dash means low coolant or "crusty" sensor prongs in reservoir. New reservoir ball is cheap (and you can see through it again). If it's throwing a code it could be the ECT sensor, which is cheap and easy to replace.

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Your coolant is low, or the sensor that tells you it is low is faulty.

If you didn’t have problems before your coolant flush & you have problems now you must have an air pocket & low coolant
Did you just drain the radiator or block & radiator ?

super1 said:

If you didn’t have problems before your coolant flush & you have problems now you must have an air pocket & low coolant
Did you just drain the radiator or block & radiator ?

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I'll second that. I've found air pockets difficult to remove with these engines. I suggest finding a steep hill/driveway, park nose down, and idle the engine for 5 min to see if you can get a "burp". If no hill is available, you can try jacking up the back of the car as high as you can safely.

I've also seen instructions online about how to "pump" the coolant through the hoses by squeezing a hose and blocking/releasing the upper coolant reservoir hose. I don't recall where I saw that, but you can probably find it with a search.

You should take case of this right away, because you are overheating your engine if you have an air pocket. Basically, the air gets to the pump, which then spins in air and doesn't do anything.

So when I drained it I popped the hose at the bottom of the radiator it was a quick job the car had been sitting for over a year. The weird thing about it is it only happens when I sit still for more than a minute or so or at start up. At first I thought fans but they seem to be functioning

cman9898 said:

So when I drained it I popped the hose at the bottom of the radiator it was a quick job the car had been sitting for over a year. The weird thing about it is it only happens when I sit still for more than a minute or so or at start up. At first I thought fans but they seem to be functioning

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Read what Shoebear wrote
If you have a jack you can jack up the car if not with the engine running you can massage the lower radiator hoses I would keep the cap off when you do that and let it get up to temperature


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cman9898 said:

The weird thing about it is it only happens when I sit still for more than a minute or so or at start up.

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I had the problem only at cold startup for a while.
I took the reserve bottle off and used an old steak knife to reach inside to scrape the sensor pins.
Had to do it twice to fix it.
Couldn't figure what was on them, didn't really see a difference.
Aftermarket market bottle is reasonably priced:
https://www.idparts.com/coolant-expansion-tank-1j0121407f-1001211064-p-1252.html
OEM also available there.