Code 22 Water temperature sensor circuit fault
First of all, what are the exact symptoms that tell you the engine is running too hot? The fault code is the result of unplugging the two-wire coolant temperature sensor while the ignition switch was on. The Engine Computer turns on the radiator fan relay when a specific coolant temperature is reached. Logic would dictate it would not do that with the sensor unplugged, but in fact, most computers have a back-up strategy whereby it turns the relay on when there is a fault detected in the sensor circuit. The computer knows it cannot rely on the sensor to provide accurate information, so it turns the fan on just in case the engine is going to run hot. That is why the fan runs when you unplug the sensor. That is a quick way to determine if the rest of the radiator fan circuit is working. You will want to erase the fault code when you are done so it does not confuse the next person who reads the codes.
Most engines of this era use a second coolant temperature sensor for the dash gauge. That one has just one wire.
A defective or unplugged coolant temperature sensor will not cause an engine to run hot, at least not directly. It simply reports what it sees. In some cases it can cause overheating indirectly, not from an engine defect, but from the computer not turning the fan on when it should.
Thursday, February 23rd, 2017 AT 4:18 PM