Did I just find a def filter or pump?

[newmarokie]

I was on the creeper under my 4018. On the passenger side inside rail I saw a canister made of black plastic. It had water hoses, smaller lines looking like def lines and a wire plug. I didn't mess with it as I was running out of time for the day. Anybody know what this is? Probably 2 1/2 inches in diameter and about 3 1/2 inches tall

 

[Rich W.]

I was on the creeper under my 4018. On the passenger side inside rail I saw a canister made of black plastic. It had water hoses, smaller lines looking like def lines and a wire plug. I didn't mess with it as I was running out of time for the day. Anybody know what this is? Probably 2 1/2 inches in diameter and about 3 1/2 inches tall

The DEF pump and filter assembly is attached to the lower rear of the DEF tank as you face the fill cap. You were looking at something else. I could guess but pictures will yield an accurate response.

Pics below are different views of the DEF pump and filter assembly. The fourth one points out where the filter lives. Filters cost around $45 from Bosch or $100 for the same thing with Cummins printed on the box. I recommend changing it annually (or at least carry a spare) although your maintenance manual probably says it has an interval of 150k miles or more. My guess is that number was developed for trucks that drive that much in a year.

DEF filter: