I purchased a 2016 Ram Big Horn with the 6.7 Cummings Diesel engine in July this year. I have only had to put def in it twice and each time the check engine light comes on with no codes. Any ideas what may be causing this to happen? The first time I used a cheap brand of def the second time I used blue def. It has around 102000 miles on it.

 

If the check engine light (CEL) is coming on, or has been on rather recently, there will be a code. It's possible your scan tool is not able to access the system that is triggering and recording the code. If you find someone with a professional grade scan tool that's updated for at least 2016 Rams they should be able to review the diagnostic code. Unfortunately, I have no idea why the DEF fill would trigger a CEL.

-Rod

 

Thanks Rod, I will take it somewhere and have it checked out.