Not the same issue, but I had the check engine light issue when I purchased my unit in 2012. The RV dealership told me the light was on because it was low on DEF. That was a big lie! Now who would ever think an RV dealer would be less than truthful.
I took the coach to a Freightliner dealer and a code showed it had a part (don't remember which one) failing. The Freightligner dealer replaced it and the check engine light came back on after 5 miles. I took it back and it still showed the same part failing, which they knew wasn't. At that point I left the coach for two days at the dealership. When I picked it up the dealer told me they pulled the engine wiring harness, inspected, cleaned and re-installed it. He suspected that something in the harness was lose or dirty and re-installing probably fixed the problem. (the invoice showed 12 hours of labor)
He was right it did fix the problem. That was over 4 years and 20,000 miles ago and no problem since (knock on wood)