Radiator light is on, spare tank is full of coolant. How do I get this light off?

When you say that it's full, are you referring to the coolant recovery tank? Have you checked the level in the radiator? If it's low, add coolant until the radiator is full, then replace your radiator cap.

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

Check the hose going to the expansion tank, That it is not pluged up.

The coolant level sensor is located on the passenger side of the radiator, just below the bottom of the battery. If the light comes on, you'll need to fill the plastic coolant tank. But you also need to remove the radiator cap and fill the radiator itself. Only open the radiator when the engine is cold. If the radiator is full, and you are positive it's full, then the sensor needs to be replaced.

If the antifreeze is full, (In the radiator, not the overflow tank) And the light is still on, replace the level sensor in the passenger side radiator tank.

Hi there,

The radiator should already be full of coolant.

Wait until the engine is cool before opening the radiator cap. Fill the radiator. Start the engine. Top it off again. Close it up.

Best regards
Mike

This problem is common, if the coolant level is OK, check the "coolant sensor" and clean the plug.

The low coolant sensor should be located in the passenger side radiator tank, You need to take it out and clean the sludge off of it for it to work right. Or you can just unplug it and forget about it, the light will go out and it won't cause any problems.

It sounds to me like you're low on coolant. When you checked the coolant level, did you actually open the radiator cap and make sure the radiator is full? The plastic tank you generally add coolant too is actually an 'overflow' or 'reserve' tank. There is a hose that runs from that tank to the top of the radiator so if the radiator gets low on coolant, more coolant -should- run in from the overflow tank. However in practice this does not always work. I have a Jeep that leaks coolant and experiences this exact same problem. Coolant will not run from the reserve tank into the radiator because the hose is plugged up, and whenever the radiator gets low on coolant the temp gauge will go real high and then drop, and the heater doesn't work well. This is because the cooling system of your car is supposed to be a closed system, full of coolant and no air. When coolant leaks out, the space it used to occupy is now occupied by air, which does not transfer heat well. When 'air' is passing through your cooling system, no heat can be transferred from your engine to the heater and radiator, resulting in a hot engine and no heat at the heater. Then when a pocket of water passes through the system, the temperature gauge quickly falls as the water absorbs the heat from the engine. The hot water that cools the engine is where the heater gets it's heat from as well, so when water passes through the heater core, the heater works, but when it's filled with air, it doesn't.

First check the coolant expansion tank and radiator for correct level. The radiator should be full (take the cap off when the engine is cold, doing this on a hot engine will cause hot coolant to spray out and possibly cause major burns). The expansion tank should be marked level-wise, either min-max, or min only, or max only. If the levels are right, your level sensor is probably bad. This sensor is located somewhere in the expansion tank.