Check engine light after fuel filter change

Peterbilt 579 2016
Cummin ISX

Changed oil and oil filter and everything was ok yesterday. Today I changed the fuel filter and water separator.

First the truck didn’t want to start, then after a few tries - it started. Now it starts fine, but now I get a check engine light, doesn’t disappear.

What could be the issue?
-Didn’t tighten up the filters correctly?
-Not enough fuel in the filters? (cant be since truck starts now?)
-Sensors?

Already tried the check engine reset when you turn the key to on and off 6 times but it didnt work.

 

Don’t understand your question. I re-checked the 2 sensors on the water separator a few times, but maybe the wires came unplugged or something when I was changing the filter, not sure how to check

 

I hope so, would hate to have it on all the time, even though I did everything correctly. Took it for a short drive, but still there

 

Thanks for the replies, will see if it disappears the next few days.
It was my first time changing fuel filters by myself so got scared I did something wrong, not a lot to it though