Coolant light is on, which sensor to change out?

[Maleficio]

There are two coolant sensors above the thermostat housing. I've cleaned both sensor's terminals, but no joy. The light wasn't coming on until after a few minutes of driving, now it comes on at start-up and stays.

Gas mileage is dropping fast, and exhaust odor is getting bad.

I don't know which of those two coolant sensors I need to change, and the WSM doesn't seem to indicate which one. Any idea?

Thanks.

[Mrmerlin]

check the coolant level . And the snder connection on the top of the coolant bottle
Also there is a pressure switch next to the washer tank fill tube. If your losing coolant and its not leaking the you may have a blown headgasket also consider replacing the coolant cap with a new one