On the 2001 and newer the doser is fitted to the bottom of the elbow that bolts to the inlet manifold.
The doser is like a throttle butterfly but it only close at idle so more exhaust gasses can be sucked into the engine.
If it goes faulty it can close by its self causing the car to bog down and even stall.
There is a vacuum solenoid near the egr one that controls it.
On my girlfriends 206 HDI I've removed the doser and replaced it with one from Toms car because the doser it's self is a bit restrictive.
The doser is like a throttle butterfly but it only close at idle so more exhaust gasses can be sucked into the engine.
If it goes faulty it can close by its self causing the car to bog down and even stall.
There is a vacuum solenoid near the egr one that controls it.
On my girlfriends 206 HDI I've removed the doser and replaced it with one from Toms car because the doser it's self is a bit restrictive.
