A "Service DEF" message popped up briefly on the EVIC a few weeks ago then went away. EVIC shows zero messages now. Then a CEL the other day, code P20EE. Searching the interwebs I'm not finding a consensus on what exactly throws this code. Some say the dealership with tell you it's bad DEF, in which case making the SCR repairs won't be covered under warranty. Others say the cat needs replaced. Some say just change your DEF and see if it goes away. I confess it hasn't used much over the past couple of months so it could be crystallized in the tank. Will probably try that before heading to the dealer. Just wondering if anyone here has first-hand experience with P20EE?

 

oh! the joy of owning a new truck!

 

Yep! But then again, compared to my first CTD (a 2003) the 2015 has twice the HP & torque, a fraction of the emissions and the same or better fuel mileage. Not to mention the more solid, usable tranny. The exhaust brake. The integrated trailer brake. A tow/haul mode that works. Nicer ride. More comfy seats. Better ball joints and steering box. And of course the MUCH bigger back seat. Don't get me wrong- I really, really liked my 2003 but this truck is even better in nearly every way!

But, I did pay nearly $20K more for the 2015, not counting inflation.

So I'm not complaining. Yet.

Now back to my question...anyone have experience with code P20EE?

 

I see that code just about every day. There is a service bulletin for it and some tests need to be done before replacing the SCR cat and updating the PCM. DEF quality, DEF flow rate are tested first. Replacing SCR cat has been fixing the problem. REF: SB 18-088-15

 

Sure appreciate the input, that helps a lot.

I guess worst case scenario the SCR kitty might run away and not come back.

 

Just an update. I pumped out most (1.5 gallons) of the old DEF (easy once I figured out where to disconnect the fill line- under the truck right next to the front of the rear driveshaft) and it looked fine. No crystallization, clear as water. So I didn't bother pumping out the rest. Topped it off with 2.5 gallons of fresh DEF and presto- code went away immediately. 3 days and a couple of hundred miles and it hasn't come back. Not 100% sure if changing the DEF had anything to do with it. Correlation vs Causality. So for now I'm good....I think.

 

This is only way to test DEF quality

 

Thanks for posting that, wish I'd seen it sooner, would've saved me some time trying to figure out where to pump the DEF from.

Makes you wish the truck was more descriptive with its codes, like a specific "check DEF quality" code or message on the EVIC would go a long ways toward diagnosing SCR issues. I could be wrong, but it seems like P20EE could be a lot of different things based on what I've read.

Also, I have been buying my DEF at the pump because it's cheaper and more convenient. Seems like the stuff in the jugs is a safer bet though?