doctorlock,
Your 2004 Sprinter is
NOT equipped with a Diesel Exhaust Fluid (DEF) system!
The DEF/SCR (Selective Catalyst Reduction) system is only found on 2010 and
later NCV3 Sprinters with the 3.0 liter V6 BlueTec engines.
http://en.wikipedia.org/wiki/BlueTec
You will also see Sprinter topics on the Diesel Particulate Filter (DPF).
Your 2004 Sprinter does
NOT have this technology either.
So, T1N 2002-2003 OM-612 and 2004-2006 OM-647 Sprinters do
NOT have
DEF or DPF emissions control systems.
The EPA standards for diesel engines were not as stringent back in the 2000-2006 era.
In 2007 the requirements became more stringent and the DPF filter was added for NCV3
Dodge and Freightliner Sprinters with the 3.0 V6 engine.
The requirements changed again in 2010 and the DEF/SCR system was added to make the
current model Sprinter diesels somewhat
CLEANER than most gasoline engines.
Roger