Under hood, center, front engine area, rear of water outlet, mounted in intake manifold
The coolant temperature sensor can be found on the front of the engine, near the thermostat. Remove the coolant temperature sensor retaining nut, to replace it.
Replace the reservoir with a new or used one.
If the hoses are all tight, Then the radiator must be leaking. REPLACE RADIATOR
This is an indication that your heater core is leaking. To stop the leaking you will have to replace the heater core or stop using your heater.
If it is noisy, leaking or not pumping sufficient coolant to cool the engine, replace it.
Your coolant pump is behined the fan, you will have to replace the water pump.
12 bucks Autozone
Engine Coolant Temperature (ECT) Insufficient for Closed Loop Fuel Control this also might be low on coolant. possibly the water pump is leaking. look right under the alternator for red or green coolant wet or dry. also check coolant level in radiator when engine is cool. if you see it is leaking, replace the water pump, thermostat and timing belt, along with any other seals like the crank seal, or the cam seal, you should see if they are leaking or not.
Find the leak and replace the hose/part that's leaking. It's a good time to flush your coolant system, too.
You don't have to replace it until it starts leaking coolant.
More than likely your heater core is leaking. The only fix is to replace it.
you need to replace the intake manifold gasket.