Water Temp Not Accurate



I have a 620 and Airmar Tilted Element Thru Hull ducer.

Water temp is way off, did work fine for 2 years.

Any way to determine if problem is unit or 'ducer ?
If you have a Ohm meter you could check the resistance between pins 4 and 7 on the ten pin transducer plug. Normally the temperature thermistor should read about 10K Ohms. If you don't have a meter you could take the sounder into a shop and have them plug another transducer into it on the bench to check the temperature function.

Ohms between 4 and 7 is MOL 2.

Plugged in ducer to my GP 7000F and it also read temp way off.
(out of water in 60* air showing around 32*)

Time for a new 'ducer ?
If the temp is bad in the transducer, the available repair options will depend on the transducer being used. What is the model of your transducer?

Analogue ohm meter read 12.5 I believe.

I'm beginning to wonder if connection on back of FF had a small amount of corrosion or some electrical arcing
as after several trial and errors, unit now locks in on temp pretty fast and no more "searching".
Unit is not disconnected till end of season.

Unit's in an electronics cabinet on top of console, pretty safe location.
Even so, a small arc could cause problems ?