That one Tuesday last month when three trucks showed up with the same exact problem

I swear it was like the universe was testing me. Three Freightliner Cascadias all came in on the same day with the DEF system throwing the exact same code (P204F if you're curious). First one took me 4 hours to diagnose, second one I did in 90 minutes, third one I knocked out in 45. The common culprit? A $12 plastic fitting that cracks right where it connects to the pump. Just a heads up if you start seeing that code pop up more often. Has anyone else noticed a weird pattern with certain issues hitting in waves like that?

3 comments

3 Comments

troyc1724d ago

Heard that fitting is a known weak spot.

sandra_moore3024d ago

Check the wiring harness first, like abbyhall said. I fixed mine last month and found the insulation rubbed through right where it passes the bracket. Wrapped it with good quality friction tape and ziptied it away from the edge. The fitting itself was fine, it was all the chafing causing the short.

abbyhall24d ago

Spot on about the fitting, @troyc17, but the real headache is the wiring harness chafing right behind it. That's usually what sets the code off before the plastic even fails. Seen it a bunch where just replacing the part doesn't fix it for long.