Cummins diesel question

Not an A body question, but I tried to get on Cummins forum and didn't remember my password.

I changed the fuel filter on my truck and since changing it the water in fuel light is on. I drove it to work today and it is still on. If I unplug the sensor it goes out

It isn't the 1st time i have changed it and used Fleetgard filter, never had this problem in the past.

What did I do wrong? could the sensor be bad and is it a dealer only part?

I would like to know where to get a new one before removing the filter and checking the sensor. NAPA does not have them so my guess dealer only, or the cummins repair shop.