I suppose I should post some factual data:
Sprinter
2015 3500 6 cyl.
On one of our trips at about 8000 miles we experienced low DEF warnings and within 50 to 100 miles received limited restarts.
Filling the DEF with no more than 2.5 gallons and often with a gallon or less cleared the restarts.
Stopped at Freightliner dealers in Minneapolis and at St. Paul, was told they were too busy to look at it. Maybe in a week or so could get it in. Our home is in the Portland Oregon metro area.
Continued to add DEF as needed, no more than a gallon or rarely 2 gallons with no warnings or limited restarts.
In January 2018 took in to Mercedes/Sprinter dealer in Wilsonville, Oregon (approx. 30,000 miles, 33 months on warranty), after one week could find nothing wrong.
In April, after driving 400 additional miles limited restarts on nearly full DEF and with check engine light. Returned to Wilsonville dealer on April 10, 2018. With 4 restarts remaining. Total additional miles after January 950.
Contacting dealer for status updates as of April 23, 2018, have had no return information.
My iCaresoft scanner showed:
47643.14 km since last regen (29,604 miles)
Last regen at 47643.96 km
18BC00 upper limit value for long-term adaptation of the SCR system was exceeded DTC stored
16CF00 Fault in system AdBlue – The number of possible engine starts is limited DTC stored
Engine off:
Current kilometer reading 49112 (30,517 miles)
Fill level of DPF 89.37%
Soot Level 7.11 g
Ash content 0 g
Engine on:
Soot content of DPF 5.03 g
Ash content 0 g
Engine speed 679 1/min
Pressure differential in DPF filter 7 hPa
Upstream temp of turbo 155.30 C
Upstream of DPF 143.7 C
Exhaust back pressure 1100 hPa