I've had a number of issues with my Sprinter. It sits for periods of time with long highway mile trips in between. I gets very little urban stop and go driving. The emissions warranty is extended if the vehicle is registered in one of the states that follows California emissions standards. That is 7years/70,000 miles, so the OP is a bit beyond that.
There's lots of info out there about Sprinters and their emissions controls especially if you look at Sprinter-source.com. It is a good engine with finicky emissions. There is one more reason to drive the Sprinter until it is thoroughly warmed up on the highway and that is to make sure your diesel particulate filter (DPF) has an opportunity to regenerate. DPF regen is accomplished by causing the DPF to heat enough to burn the carbon particles out so it doesn't become plugged, leaving a small amount of ash behind. It requires enough driving, fully warmed up, to complete a cycle.
Below is my emissions system history:
My AI is a 2013 model on a 2013 Sprinter. I purchased it in 2016 with 21,000 miles on it. At about 25,000 miles while on a long trip I had the EGR valve fail which put the van in limp mode. We were about 30 miles and a mountain pass West of Las Vegas toward Pahrump. That resulted in a tow to the Mercedes dealer. The emissions warranty covered it.
Later the same trip in the Port Aransas, TX, area, I had a check engine light, so I had it checked at the Mercedes dealer in Corpus Christi. It was the DEF heater. The service rep told me that is was no big deal, because we were somewhere warm, and it was something only important in cold climates. This was at about 26,000 miles. This wasn't entirely accurate.
About 500 miles later I noticed a dusting of a white powder inside the exhaust pipe, and by the time we got to Biloxi, there was a DEFcicle hanging down from the exhaust pipe. There was no limp mode or CEL for that event, but it was obvious that the DEF system was overdosing.
The Mercedes dealer in Mobile diagnosed the DEF heater, and both the upstream and downstream NOX sensors as defective. That was also covered under the emissions warranty.
The final emissions issue was a defective EGR cooler at 43,000 miles which was not covered under the emissions warranty according to my local dealer, but they "goodwilled" the repair because I had been diligent at having the van serviced. There was a CEL for that, but the van did not go to limp mode.
The van now has 49,000 miles, and I notice the decreasing frequency of emissions related repair. I am hoping that the troublesome components have been replaced with updated later versions that will be reliable. Other than the listed issues, the van has been a pleasure.