Technical DPF regeneration failed.

[Golonko]

Hi everyone,

I’m opening a new thread to describe the current status of an issue I've been dealing with for a while, related to DPF regeneration.

My vehicle is a Fiat Ducato 2.3 Multijet 150 (2013) motorhome. Over the last year, many components have been replaced or checked:

Reconditioned engine

Reconditioned and tested injectors

Reconditioned turbo

New DPF + front catalyst (DOC)

New differential pressure and temperature sensors

New glow plugs and PCV valve

ECU recently updated via Pass-Thru with official Fiat software (focused on regen and injection)


Current symptoms:

Regeneration attempts happen roughly every 800–1000 km

Since the new DPF, white smoke is still present during regen attempts, but less extreme than before

Most attempts are interrupted: the dashboard briefly shows ignition/reset messages, although the engine stays on

After multiple failed attempts, soot level suddenly drops (e.g. from 85% to 32%), but the ECU does not record a completed regeneration — the "km since last regen" counter remains unchanged

OBD data shows a clear drop in DPF temperature at the exact moment of the interruption


Despite all components being replaced or updated, the regeneration process still fails to complete properly. Any ideas or similar experiences?

Thanks for your help.

 

[lycopersicum]

Can you post the data (temp and pressure)? During a regen if possible, otherwise during normal driving.

Has the ECU been replaced or only updated?

Besides the ECU the last components involved in the emissions control system that haven't been changed yet would be the lambda sensor and the wiring...

 

[Golonko]

Here you have the values registered when the ignition goes down for a moment. Sorry, is was taken in spanish. The first is temperature. The second is pressure.

The first image is the temperature when it fails. The second is the pressure sensor.

 

[lycopersicum]

The way both signals drop to zero indicates an electrical problem.

Either an interruption in power to the sensors (bad wiring between ECU and DPF?).

Or an ECU glitch that stops the recording briefly.

Do you ever observe the sensor signal dropping to zero like this during normal driving?

 

[Golonko]

Not, only at the moment of DPF regeneration. In fact, i think that when the regeneration finish.
Then It is not registered and after a few kilometers, It try to regenerate again. Yesterday It did five attempts. Then i stopped for a half of an hour and then the porcentaje go down from 85 to 30.

 

[lycopersicum]

With the data you've posted I think we have proof of some sort of ECU glitch.

It could simply be because the ECU is faulty.

It could also be because the ECU detects values that are abnormal in a way it doesn't know how to handle. So it defaults to resetting just to be safe.

And it could be because of a bad electrical connection somewhere (checked the earth strap?) that is just barely OK in normal conditions but somehow causes the voltage to drop at a particular stage of the regen (maybe second stage regen when there's one extra injection per cycle compared to first stage).

I'm sorry it sounds like a tricky problem to diagnose

1. Are you able to tell if the peak temperature tends to be a bit lower when it finally manages to drop to 30%, vs times when it doesn't drop? I still think your regen temps are too high.

2. Can you tell if the signal from sensors that are not physically located near the DPF also drops to zero during the glitch?

 

[Golonko]

I’m not sure how to check the earth strap myself, but I’ll mention it to a mechanic and have it looked at properly.

Thanks

 

[AsdaPricey]

Hello @Golonko

Alongside the fact that the regeneration fails what other fault codes are there?

Did the new DPF get registered properly including resetting the countdown mileage to needing a new unit?

Is the ambient temperature (sensor in mirror head) on the dash reading correctly?

Perhaps search amongst O’Rileys Autos on YouTube channel in case you can glean any help from them - his daily work involves solving DPF issues.

 

[Golonko]

Thanks a lot for the suggestions — really appreciated.

1. The main fault codes I’ve seen are P2002, P2106, and sometimes P0238, especially when the DPF gets very saturated.


2. When the new DPF was installed, the mechanic had some trouble resetting the learned values. I’m not 100% sure it was done properly — I’ll try to confirm that.


3. The outside temperature shown on the dash seems accurate and changes normally, but I’ll make sure the mirror sensor is actually being read correctly.


4. I didn’t know about O’Rileys Autos — great tip, I’ll check his channel.