Below is some important information when fitting a DPF on a Euro 5 Ford & some other Euro 5 emissions vehicles
The most common cause of the DPF becoming blocked is a faulty/blocked fuel vaporiser. When the fuel vaporiser is faulty/blocked no diesel is introduced into the exhaust during regeneration thus preventing it from reaching the required temperature for a successful regeneration therefore causing the DPF to become blocked.
These vehicles are fitted with a fuel vaporiser unit in the exhaust downpipe just after the turbo and before the flexible joint. The purpose of this is to inject diesel into the hot exhaust gasses to heat the DPF. The fuel vaporiser is fed with a supply of diesel from a metering pump. Inside the vaporiser is a small glow plug which is pulse controlled by the ECU along with the metering pump.
What goes wrong?
The fuel vaporiser is in a stream of hot exhaust gasses and as a result eventually gets blocked. Therefore the DPF never gets up to temperature, the regeneration fails and the DPF becomes blocked.
What is an easy test to see if the vaporiser is blocked?
If you look up at the unit you'll see the diesel supply pipe.
Disconnect this from the fuel vaporiser and then connect a vacuum tester to the fuel vaporiser.
If you can pull any appreciative amount of vacuum on the gauge then you have a blockage.
Also the fuse that feeds the fuel vaporiser is known to randomly fail.
This will set a fault code in the ECU.
The fuse is located in the fuse box in the engine bay towards the front of the car.
1) Check the differential pressure sensor is working correctly.
2) Check that the pressure hoses are fitted the correct way round.
3) Check the pressure hoses for splits & blockages.
4) Check the fuel vaporiser is working correctly.
5) If not - check the fuse for the fuel vaporiser.
6) Check if the fuel vaporiser is blocked.
7) Check the pump that feeds the fuel vaporiser is working.
8) If the fuel vaporiser is replaced ensure it is primed correctly.
9) Check that the engine cooling fan is working.
10) Check the EGR system.
11) Fuel injectors – remove and send for specialist testing.
12) Check the oxygen sensor is working correctly.
13) Check the catalytic converter is working correctly and that the monolith is not clogged or coated as the Cat is required to generate additional heat for the regeneration process to be successful.
When we replace these units in our workshop we always replace the fuel vaporiser at the same time and as far as we are aware most Ford dealers adopt the same policy.