Answer to Question 4: Neither Technician A nor Technician B is correct. The Diesel Particulate Filter (DPF) should not be removed and cleaned once a year to minimize DPF sintering. Instead, it should be actively regenerated when it becomes full of soot. There is no need to regenerate the DPF at every oil change.
Answer to Question 5: Technician B is correct. Only a Diesel Particulate Filter (DPF) can remove particulate emissions from the exhaust. However, Technician A is incorrect. DPFs are still used in HD diesel engines, and they were not replaced by Selective Catalytic Reduction (SCR) systems in 2010. Instead, SCR systems are often used in conjunction with DPFs to reduce both particulate matter and NOx emissions.