2 check engine lights on and my DEF fuel light on but I just filled DEF tank

was having the same lights on my self 2 weeks ago, only the DEF light was flashing, but tank was full
shortly after required tow to Freightliner, metering valve was plugged, airline to purge it had rubbed through
couldn't purge line and plugged up not allowing regen, should have stopped there on the way. $910 tow bill , 2012 Cascadia DD-15

 

Your check engine lite means you probably have an issue with your particulate filter, since your DEF lite is on this means you have a filter clogged or water has caused your DEF filter to clog. does not mean that you are low on DEF, but that there is a concern with the DEF system, same as the check engine and the yellow engine lite means you are getting a secondary problem with your particulate filter. Had same issues exactly, hope you have better luck with your repairs than I had.

 

Might just need to have the dealer clear low DEF codes.

Does it tell you which codes are active on your ICU?

 

Same problem here. My force Regen doesn't work. I let it get to one green square '12 detroit fill up and boom blinking yellow. I was just limited to 55 still blinking check engine light. I figure ill get a shop to try a forced Regan. I just paid 1419 to replace limiting valve, clean filters valves and run 3 regens. In shop over nite. Now three months later its back to a problem. Nox sensors low but good. Nickle and dime. Hope this Regen works before I get 5 limited. Got a heavy on me!

 

Wash wheels and polish steps too. sometime helps in this situation.
or use search button. Low nox conversion and READ IT.

 

This happened to me , changed both sensor's did a reset and all good .

 

Have had this problem for 7 months been to shop many times and have spent 8k so far. Engine light and blinking def light when I go up steep hill. Only happens once every few weeks. It derates to 55 for 30 miles then lights go off. It gets 90 percent conversion when in shop. Any suggestions?

 

low nox conversion happens during driving. something happens with def delivery to 1-box ...
if your truck is 2014 and up most likely def awning kit is not installed.