If someone can provide the sensor and wiring diagram, i'd be willing to drill my active tank and bypass the OEM sensor since i have the temp code on at the moment and it doesnt go away :/

I think the tank doesnt have to be drilled. The computer will accept the temperature that is close to the ambient. With engine running the temp AROUND the tank will be a bit higher than ambient, as in the ISTA example.

So the sensor will go on the tank somewhere, doesnt have to make contact with the DEF fluid? What about for cold climates since im in NY. Will this still work?

Probably if it is attached to the container and there is some heatshielding over it it should be pretty accurate.

Ozer, if you can find the connector for the temp sensor in the tank, see how many wires it has. I would expect 2 wires, but it could be more.

Do you have software or a scan tool that can "read" the current temperature of the DEF tank?

Does the DEF tank error light the SES/CEL/MIL and does it provide Freeze Frame data that may have the tank temperature when the error occurred?

Basic thermistor sensors are usually pretty reliable, the problem is most likely with bad solder joints on the sensor itself or wiring connections at the connector.

I am not sure why the DEF temperature is important, I do know that the DEF will slush or freeze and maybe the temp sensor main purpose is to prohibit the DEF from being used when it gets close to slush temperature?

Maybe the temp is also used to precisely adjust the DEF amount as well, I have no idea.
I assume the ideal position for the sensor is in the bottom of the tank so it stays submerged in the DEF?

But a working sensor near the DEF tank may be helpful and work out.

My guess too. Perhaps someone with more knowledge on DEF systems may chime in, but I dont believe that a few degree inaccuracy of the fluid will have catastrophic consequences.

I will see if i can unplug it this weekend and see if anything is corroded with the harness. I only have couple apps, Carly and Fusion which has freeze frame but not sure if it shows DEF temp. I will check. I can see the code in pending status and after a while it throws the CEL.

It is because the temp sensor values are used by DDE to heat the DEF in active tank as there is a electric heater inside the active tank.

If you have a good multimeter, I would be curious to see what the sensors current resistance value is (I know it's "bad").

If only this is the function, placing the sensor outside with some heat shielding will do the job.
This may turn into a 10 minute job with $100s of savings ;)