Question: Was there ever another root cause than clogged LPEGR Cooler reported for P0401/P0402/P0238 ?
The clogged cooler is not the root cause. Lets use the 5 whys
why do I get a P0401 et al?
Blocked cooler
why do I get a Blocked cooler?
excessive soot from DPF
why do I get excessive soot from DPF?
Cracked DPF
why do I get Cracked DPF?
Excessive temperature bad conditions durring regeneration
why do I get Excessive temperature durring regeneration?
Now we are getting closer to the root cause.
The clogged cooler is the reason for the PO401., but what is root cause.
What else do we know to drill further down into the cause
DPF gets cracked,but what causes it to crack?
1 the injection of fuel during regeneration is done using the standard injectors and not the world class method of a fifth injector. This gives the injectors a hard time and damage/ poor control more likely cleanliness issues and quality of jet control.
The function of the regeneration process is to increase the temperature above normal to facilitate the burning/conversion of soot to ash. If overfuelled we could have much higher temperature leading to cracking or melting
2 Is it poor dpf design ? Or is it poor quality dpf inner filter component ?
poor Design an interesting question, Has the part number changed since 2016 no, so design probably deemed ok, however the dpf fitted to the twin egr model was of a new concept. These engines were the first to use production variant of what is now standard manufacturing technique. Now Because of my work in materials and process development I am well aware that problems can occur in early production phases of complex ceramic processess. So were early DPFs dodgy? or more suseptible to poor temperature control?
3 Software control. The ecu software version started at 13 but by 2018 was at least 24 my van was updated to 28 in March 2019 (the latest position as I understand it is Manual V28 Comformatic V32.
Poor regen algorithm, other overfuelling issues, better callibration data with experiance of engine hours running .
4 Other Factors. It is known that number of vans came from Sevel with the wrong MAP fitted (supply issues early on) this could lead to incorrect calibration and temperature issues. In first years there were also a number of Differential DPF sensors failed and 2 versions fitted, this sensor is important in the regen process, was it important in the failure process?
Question: Was there ever another root cause than clogged LPEGR Cooler reported for P0401/P0402/P0238 ?
The definition/ reporting of a blocked cooler does not come from a collection of Fault codes but from the analysis of live data,historical data and physical observation, however, given the selection of codes the live data eventualy points to the blocked cooler.
All mostly guesswork of course (or analysis of data). I have no connection to Fiat or have had discussion with Fiat employees. I have been a Manufacturing, Production, Process Engineer within the Aerospace Industry for a while. Unfortunately i have no specific Automotive software experiance or equipment to reverse engineer Fiats software.
Hope this been helpful.