T1N Turbo Resonator
From Sprinter-Wiki
T1N Turbo Resonator is found on OM647 motors in model years 2004 - 2006 T1N's. The latest version of the Turbo Resonator is Q5 (p/n:05137154AB).
There are no apparent physical differences between the older Q4 and the newer Q5, except maybe the glue that holds the halves together. Problems occur when the two halves separate and the Sprinter goes into Limp-Home Mode. Most Turbo Resonator failures occur on heavily loaded Sprinter RV conversions.