Intake manifold cleaning – The intake manifold is also a passageway for the fuel mixture, and distributes both the air and fuel.
Intake valves cleaning – Since fuel hits the heated intake valves, deposits will eventually form on the inside or at the back of the intake valves. This needs to be cleaned out periodically, or the car will become unreliable and consume more fuel, resulting in a worse gas mileage.
DPF cleaning – Diesel particulate filters trap soot from the exhaust and ash from motor oil. Most soots are burned off in the course of a CRDI car’s operations, but ash stays in the filter’s honeycomb substrate and is removed through periodic services.