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Problems During Dpf Regeneration


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Hi all.

I have a problem with my 2008 1.6 TDCI Ford Focus that has around 175.000KM (130.000miles).

My focus is running completely normally until the DPF regeneration starts. I know that the problem is during the DPF regeneration, because I have OBD2 connected and I am monitoring inlet air temperature. When this temperature rises form normal 20°C (+/-10°C) to 50-60+°C then DPF regeneration starts. This usually takes around 10-15km (10 miles) and then inlet temperature returns to normal.

So, every thing is normal, but when DPF regenerations starts (usually on highways) then focus starts to falters, there is big loss of power and recently there is also some strange sound from turbine (sounds like turbine occasionally hits metal housing). In order to prevent heavy faltering and turbine damage, I have to be very gentle on throttle and drive at low input power and around 1000-1500 RPM. (i do not want to stop the regeneration process). It there is straight road i can maintain around 60mph, but it there is some uphill slope i can only do around 25-30mph!! But when the regeneration process is completed, then everything returns to normal, power is restored and there is no more strange sounds and I can go over 100mph without a problem. Like a miracle. :)

I get following codes:



One remark, I have a feeling that my mpg is not as good as it used to be?

Any Ideas?

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here :-

P2459 - Diesel Particulate Filer: Regeneration Frequency
Possible Symptoms
  • MIL on

Possible Causes
  • Heavy loads on engine (towing)
  • Short trips in cold weather
  • Faulty Exhaust Pressure Sensors (G450/G451)

possible solution

Change driving habits,Inspect Exhaust Pressure Sensors (G450/G451) as per factory repair manual. Special Notes

Depending on driving habits, soot can build up quickly in the DPF, thus requiring more frequent regenerations than normal

P0234 - Boost Pressure Regulation: Limit Exceeded (Overboost Condition)
Possible Symptoms
  • Malfunction Indicator Light (MIL) ON
  • Boost Pressure too high
  • Reduced Power Output

Possible Causes
  • Hoses incorrectly connected, disconnected, blocked or leaking
  • Boost Pressure Control Valve (N75) faulty
  • Boost Pressure Sensor (G31) faulty
  • Turbo Charger stuck/faulty

Possible Solutions
  • Check Charge Pressure Control System
    • Perform Output Test (to check the Turbo Charger)
    • Perform Basic Setting (to check the Charge Pressure Control)
    • Perform Pressure Test to locate Leaks
  • Check/Replace Boost Pressure Control Valve (N75)
  • Check/Replace Boost Pressure Sensor (G31)
  • Check/Replace Turbo Charger
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Thank you Martyn.

Boost pressure valve/ sensor seems good place to start. I am looking for something that should get switched on or off during dpf regeneration and it doesn't. Sticking egr also?

Ed, yes, i meant 130kmh of course (not from UK) ;)

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A few more words on this topic...

As I said, I am looking for something that goes wrong only during dpf regeneration. In all other conditions cars runs normally, has good power, no turbo issues, etc. But during dpf regenerations, car is terrible.

I already went to Ford mechanics for quick check and they gave me more general answers, nothing specific. What I am afraid is if i let them do the "research" they will take the easy way and start with changing of possible components, each of them for 100€ or soo until the problem will be resolved (Murphy says that faulty component will be the last on list :) ). I don't want to change good components, I would only like to change the faulty one.

Does any one know how regeneration process works? Which valves opens and which one closes?

There is some data in following document, but not all ( http://www.fordpers.be/content/assets/news-2011/pdf/Ford_tech_FAP_TDCi_NL.PDF)

Since focus has 175.000km, and that there is dpf frequency problem and since I thing that mileage is not as good as it was, my assumption is that I may have EGR problems. EGR is starting to stick (no errors jet) so there is poor combustions with more carbon, dpf has to regenerate more often and if EGR has to be completely closed during dpf regeneration and it isn't.....This can cause my problems...or not? :)

Any ideas would be appreciated.


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