Follow the radiator hose to the block on the drivers side. It will be clamped to a hose connection where the t-stat is. Right next to that connection on the right is the PCM coolant temp sensor.
The air intake sensor is located in the air tube connecting to the air cleaner box. The tube runs driver's side to passenger's side at radiator location and is on the bottom side of the tube. Make a note.....the coolant temperature sensor and air intake sensor are the same.
coolant temperature sensor is the right of the coolant outlet line on the top of the engine when looking at while standing in front of the truck. it has a black two prong clip attached to the sensor. the oil temp switch is to the left of the coolant outlet line. it has a single black wire coming off of it.
Trouble code 21 presents two possibilities. Coolant temperature out of specified range or coolant temperature sensor out of specified range. If you are not overheating try changing the sensor. It's inexpensive and easy enough for everyday home mechanic. We own a 92 Tempo GL with the 2.3 motor.
You need to check coolant temperature sensor and the water pump.
Next to the thermostat housing.
Directly underneath the distributor, plugs into the end of the head. Almost can't see it until you remove the distributor.
The Coolant Temperature Sensor is located on the driver's side of the lower intake manifold, just under the throttle body. It will have an electrical plug comining out of one end.
There are 2 coolant temperature sensors. The first one is located near the therostat housing at the upper rad hose. The second one is located on the back of the block near the EGR valve and ignition coil
If it's cold outside, it's because ECU use ambient temperature sensor and coolant sensor to manage RPMs. After you start the car the coolant temperature is low and ECU sets RPMs very high, when it gets warm RPMs drop down until engine reaches operating temperature.
ON my 92 sundance the sensor is located on the side of the themostat housing. It also controls the cooling fan. If it quits, start the car let it warm up and unplug the sensor at the housing. If the fan comes on the sensor is bad.
sure you need to you can do it fast but you will need to add coolant and myu advice is to when you need to replace the thermostat its the time to replace the coolant
low coolant sensor location is on the right side of radiator tank ( passenger side of vehicle) looking at it after you open hood it is on your left side. easy way to view it is to remove right side headlamp assembly (passenger side, not drivers side) it is a black plastic square with a two wire connector. this is the"low coolant" lamp warning sensor, not the coolant temperature sensor, which sends signal to temp. gauge.