What model year engine did gm start using def in duramax?
General Motors started using DEF (Diesel Exhaust Fluid) in their Duramax engines with the 2011 model year.
This was the introduction of the LML engine, which was the first Duramax to meet the EPA's stricter emissions standards. The DEF system is essential for the Selective Catalytic Reduction (SCR) system that reduces NOx emissions.
