DPF light DEF codes and Stop Engine

[PaulTNaples]

Well…this is an interesting issue. Filled up with fuel and DEF in Grand Junction. Made our way to Ouray, CO. No previous issues with DEF or CEL.
Left Ouray traveling south to Durango on the Million Dollar highway. Climbed to 11,300’ over Red Mountain Pass. Then down to Silverton and back up and over 2 more passes. 10,500’. Long down hill to Durango. Kept the rig in 3 and 4 gear on the way down. 15 miles from the campground blinking DPF, then solid DPF, the. stop engine. Pulled over. Strong smell of burnt plastic. Started up, no stop engine. Blinking DPF, then solid DPF. Stop engine off and on.
Stopped for 2 days. Research indicated that a forced regen was required.
Left the campground and called Farmington, NM Freightliner. Same issues as before. Kept the RPM’s at 2200-2500. Flashing DPF and Stop Engine went away. MIL light stayed on.
Freightliner diagnosed that there was a high pressure code for the DEF. Here is the takeaway. Just like everything else, when you move up in altitude from 6500’ to 11,500’ anything in a closed environment has increased pressure.
When heading up in altitude, open the DEF tank cap and let the pressure out.
Hats off the Farmington Freightliner. No issues and they did the fuel rail recall too. Out in 4 hours and made it to Amarillo by 10pm.

[Dutch Star Don]

Good info....when all the plastic bottles and packages start to swell inside the coach, it's time to open the DEF cap.