Have a problem with your Engine Coolant Thermostat?

Here you can find some answers and advices regarding the Engine Coolant Thermostat.

You are not sure is your thermostat functional or not?

If it was checked only by operating the heater element, it probably will not be enough to open the thermostat fully. If it was checked only while submerged in water heated up to at least 206 F, It should open most of the way. If the heater is energized while the the thermostat is submerged in water at or above 206 F, it should become fully open. be careful not to allow the electrical connector to become submerged.

You are receiving an error code of P0118?

If you are receiving an error code of P0118 which means the thermostat has the wrong sensor on it, double check this before condemning the thermostat/sensor: The coolant temp sensor and the crankcase vent hose heater connectors have the same connector configuration and they are on the same harness. The two connectors can be unintentionally swapped during installation of the thermostat assembly. If they are swapped a code 2F19/P0118 will set due to an incorrect high signal on the coolant temp sensor circuit. The wires going to the coolant temp sensor connector should be pin 1 yellow and pin 2 white. Also, if the thermostat is not opening verify that the cooling system has been properly vented/bled. If there is air trapped in the cooling system the thermostat will not work properly.

Thermostat makes a noise when you shake it?

The noise is probably the jiggle pin rattling around. The jiggle pin is the little piece located on the outer circumference of the thermostat. It prevents air from getting trapped at the thermostat before it opens. The thermostat should be installed with the jiggle pin facing upward at the top so that any air at the top can be bled from the system.


When changing a water pump, it is recommended to change a thermostat as well. They are both located in the same area so it is not really much extra work to get to the thermostat. Both the water pump and thermostat are common failures on this engine and the cooling system will already be open for repairs, so it's always recommend to do them both at the same time.

Metal Engine Coolant Thermostat Housing Dorman For Justy 1.2L L3 1987-1992 | 902-5111
Metal Engine Coolant Thermostat Housing Dorman For Justy 1.2L L3 1987-1992 | 902-5111

One x 902-5111 - Engine Coolant Thermostat Housing

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