Temperature Sensor Malfunction ... reads water at 40C when its closer to 20C

I have a Jandy LRZE 350btu heater. Its 4 years old. Saltwater pool.

For the past few days, as soon as we start the pool, the temperature sensor seems to read the water as being 40C even though its actually around 23C according to the thermometer in the pool. And its been really chilly the past few days so the 23C is accurate. Bottom line the heater won't turn on as the sensor thinks it way past the set temperature.

Now I have checked the water flow, the filters and anything else that I can think of. I have cycled the power to the heater. It seems from what I have read that this is a problem with the sensor.

Can anyone confirm they have ever had this problem. I know the part number (R0477300) and it seems easily accessed, but I am wondering if I am over looking anything. Also can this sensor be cleaned or is is it simply 'done' and needs replacing?
 
Disconnect the sensor and then using a ohm meter, measure the resistance between the two wires. Since you are in the Celsius range, that should be 104 F which the ohm reading would be 5.327K ohms. If that is what you are getting then yes the sensor needs to be replaced. If not, then we have a board issue possibly.
 
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