Fiat suggesting new DPF because P401 - why? (1 Viewer)

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Jane And Rog

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Since early Feb, our 2019 Dual EGR Ducato has been showing intermittent P401/402 faults.

We have had the low pressure EGR replaced by a a local garage and Fiat have updated the ECU software. Neither of these fixed the problem. The latest error codes are:
P0401-61 Air control negative governor deviation low air quantity - Signal calculation failure
P0402-61 Air tracking control system - Signal calculation failure

Fiat's latest suggestion is to replace the injectors, the DPF and EGR (again but lets not think about that).

This is costing £6000 in parts and Fiat are paying half of that. Annoyingly, yesterday, the wrong DPF arrived from Italy and the right part is now showing out of stock on their system.

The dealer's technician says that the van is drivable but with the engine light on the DPF will not regenerate and we risk it getting blocked and then refusing to start. The DPF is currently showing 25% full - which seems like it has regenerated in the last few hundred miles.

So, I'm trying to understand why Fiat are suggesting a new DPF and what risk we face if we get the new injectors fitted and drive on the old DPF.
 
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Dec 17, 2019
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Blimey, I hope you get it sorted soon. Our van is the same age🤞 With the volume of production for Ducato’s it seems baffling that these parts aren’t routinely held in stock as they must get through a lot!
 
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Jane And Rog

Jane And Rog

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Further data point - on the phone the garage said that the DPF clogging was 25%. which my googling seems to show is within normal parameters.
 
Jul 28, 2008
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Is yours a pre-ad blue version?
Ignore DPF full data - that is calculated and can be reset.

Firing parts cannon is fiats normal approach

The EGR can be blocked, and the DPF can break - and this appears to be down to over fueling caused by the ECU config.
The updating the ECU is can be a fix, but has to be done WELL in advance of any physical issues. (eg it stops it happening, and the update can't fix DPF or clean EGR)

So hence when we bought our van I insist on ECU being checked/updated on each service (and do ECU dump pre/post to confirm)


Not great reading, but huge amounts of effort gone in this thread.... https://www.fiatforum.com/threads/d...t-do-i-check-next.491167/page-48#post-4747022

Also I think they are a member here, I loose track @1andonly ?

So would suggest you get a cuppa and study the above thread.

Personally, I'd check/confirm the ECU version, and get DPF cleaned/checked and EGR cleaned/checked by a 3rd party expert. See also https://www.youtube.com/@ORileysAutos and see how many major issues he fixes with basic diagnostics, and see the amount of part cannon failures.... I'd book in with him personally! May well need new DPF (if core broken) but reading ECU "soot" is not giving an answer as its not a real number,
 
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Jane And Rog

Jane And Rog

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Blimey, I hope you get it sorted soon. Our van is the same age🤞 With the volume of production for Ducato’s it seems baffling that these parts aren’t routinely held in stock as they must get through a lot!
We've been given a number for parts in Italy, but they don't answer the phone. Today we're going back to the garage asking why the DPF needs changing at all, given that the error codes are EGR, and they detected a fault in the injectors which they have managed to obtain so could replace.

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Jane And Rog

Jane And Rog

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Is yours a pre-ad blue version?
Ignore DPF full data - that is calculated and can be reset.

Firing parts cannon is fiats normal approach

The EGR can be blocked, and the DPF can break - and this appears to be down to over fueling caused by the ECU config.
The updating the ECU is can be a fix, but has to be done WELL in advance of any physical issues. So hence when we bought our van I insist on ECU being checked/updated on each service (and do ECU dump pre/post to confirm)


Not great reading, but huge amounts of effort gone in this thread.... https://www.fiatforum.com/threads/d...t-do-i-check-next.491167/page-48#post-4747022

Also I think they are a member here, I loose track @1andonly ?

So would suggest you get a cuppa and study the above thread.

Yes, pre Ad Blue. I think it's a 2018 base vehicle. I've been trying to read that thread and many like it, but it's a lot for me to take in when I'm no expert.
 
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Jul 28, 2008
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Yes, pre Ad Blue. I think it's a 2018 base vehicle. I've been trying to read that thread and many like it, but it's a lot for me to take in when I'm no expert.
Certainly see that thread then.
(above post edited with extra links)

the issue seems to be that specific model, and tends to be on vehicles that have been used/serviced without ECU being updated (Hence I keep saying cheap services at mates garages or DIY are not worth it on these vans - you need the updates). So if ECU not updated for years then the damage may be done.

But the fiat forum thread is long but really informative. Worth a detailed read before the usual part replacements....
 
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Jane And Rog

Jane And Rog

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Personally, I'd check/confirm the ECU version, and get DPF cleaned/checked and EGR cleaned/checked by a 3rd party expert. See also https://www.youtube.com/@ORileysAutos and see how many major issues he fixes with basic diagnostics, and see the amount of part cannon failures.... I'd book in with him personally! May well need new DPF (if core broken) but reading ECU "soot" is not giving an answer as its not a real number,

Would getting the idling DPF pressure in mBar be a true reading of whether the DPF is working?
 
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Jane And Rog

Jane And Rog

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We spoke to the dealer just now and got a little more detail. They think the problem is excessive leakage on the injectors and they are replacing all three parts because that's what's documented in the "Service News Bulletin" from Fiat: injectors, DPF and EGR are always replaced as a set. If we just ask them to replace the injectors it'll not be covered by their service warranty.

Jane's knowledge from the Fiat Forum thread managed to bamboozle the dealer's gate keeper enough that we're now waiting on a call back from the technician.

activecampers that Service News will be your parts cannon...

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Jane And Rog

Jane And Rog

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Somewhat aware we're talking to ourselves in this thread but... in answer to my initial question: we spoke to the technician - well we spoke to someone standing next to the technician - and the injectors and DPF units have been updated and need to be upgraded as a pair. ¯\_ (ツ)_/¯
 

RedFrame

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Somewhat aware we're talking to ourselves in this thread but... in answer to my initial question: we spoke to the technician - well we spoke to someone standing next to the technician - and the injectors and DPF units have been updated and need to be upgraded as a pair. ¯\_ (ツ)_/¯
Has anyone suggested replacing the DPF pressure sensor(s)? I did this and it resolved all my issues.

Cheers
Red.
 
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Further data point - on the phone the garage said that the DPF clogging was 25%. which my googling seems to show is within normal parameters.
On my friends Citroën C5 the dpf when new, starts at 22% so 25 % means it is basically clean
Ignore DPF full data - that is calculated and can be reset.
This^^^^^^^^^^

& as activecampers said in post #4 O'reilys is the you tube to watch. He fixes stuff diagnostically that dealers have fired the parts cannon at simply because he understands what the computer is telling him.
 
Jul 28, 2008
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Would getting the idling DPF pressure in mBar be a true reading of whether the DPF is working?
Its the differential thats important - e.g. difference between pre and post - so depends what you read and where
A high reading (that increases with RPM) suggests blocked
A very low reading that doesn't change much with RPM suggests it could be fractured internally.
Non changing numbers or weird numbers, or not following RPM could suggest sensors.
As for the "known good" readings, see the fiat thread.
Also see example ducatos on the youtube channel I suggested.

Anyone who suggests forced DPF regens is a muppet generally, as there is a reason the DPF is blocked, and forcing a regen and resetting soot count looks good on the ECU data but does fk all. Also if there is an issue, a forced regen can cause more damage on DPF.

Main dealer diagnostic skills tend to be very much lacking, following a check sheet. (e.g. I had a transit engine issue - no turbo power. Had I had the computer system I'd have said "actuate turbo" and seen what happened, or not. But no - £700 they never even did that. Had they done that, they'd have seen the EGR actuate instead! And then gone, thats weird - and traced a "swapped" pair of vacuum control tubes. Who swapped remained a mystery.... But on no £500+ later and their diagnostic was "new intercooler as the MAP sensor is faulty" - even though I'd already proven it was not faulty (pressure and vacuum tested it and ECU was correct. Anyway, swapped sensor in car park (as 3rd party parts place had a sensor without changing the intercooler, proved it wasn't that, ford said "oh well book in another session in a few weeks!!!!)

So have little trust in them TBH.....

(Same as BT OR engineer who visited my dad - "oh we can put the socket here, you are now on full fiber so your wifi will be stonger". Hmm. A little knowledge is dangerous)

Anyway, I've ranted enough and feel your pain.

(Did you buy 2nd hand? I fear many that have been serviced cheaply and sold on will have this problem and bite unsuspecting new owners :( )

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Jane And Rog

Jane And Rog

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On my friends Citroën C5 the dpf when new, starts at 22% so 25 % means it is basically clean

This^^^^^^^^^^

& as activecampers said in post #4 O'reilys is the you tube to watch. He fixes stuff diagnostically that dealers have fired the parts cannon at simply because he understands what the computer is telling him.
We’re already in hock to Fiat Canterbury for all the parts, but this will be our next port of call. Thanks.
 
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Jane And Rog

Jane And Rog

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Its the differential thats important - e.g. difference between pre and post - so depends what you read and where
A high reading (that increases with RPM) suggests blocked
A very low reading that doesn't change much with RPM suggests it could be fractured internally.
Non changing numbers or weird numbers, or not following RPM could suggest sensors.
As for the "known good" readings, see the fiat thread.
Also see example ducatos on the youtube channel I suggested.

Anyone who suggests forced DPF regens is a muppet generally, as there is a reason the DPF is blocked, and forcing a regen and resetting soot count looks good on the ECU data but does fk all. Also if there is an issue, a forced regen can cause more damage on DPF.

Main dealer diagnostic skills tend to be very much lacking, following a check sheet. (e.g. I had a transit engine issue - no turbo power. Had I had the computer system I'd have said "actuate turbo" and seen what happened, or not. But no - £700 they never even did that. Had they done that, they'd have seen the EGR actuate instead! And then gone, thats weird - and traced a "swapped" pair of vacuum control tubes. Who swapped remained a mystery.... But on no £500+ later and their diagnostic was "new intercooler as the MAP sensor is faulty" - even though I'd already proven it was not faulty (pressure and vacuum tested it and ECU was correct. Anyway, swapped sensor in car park (as 3rd party parts place had a sensor without changing the intercooler, proved it wasn't that, ford said "oh well book in another session in a few weeks!!!!)

So have little trust in them TBH.....

(Same as BT OR engineer who visited my dad - "oh we can put the socket here, you are now on full fiber so your wifi will be stonger". Hmm. A little knowledge is dangerous)

Anyway, I've ranted enough and feel your pain.

(Did you buy 2nd hand? I fear many that have been serviced cheaply and sold on will have this problem and bite unsuspecting new owners :( )

We got a pressure differential reading from them today - 100mBar, which is massive, and doesn’t seem to fit the 25% to me (Jane, I know Rog is better at the boy stuff).

As I said we’re in so deep cost-wise now it would be stupid to pull out with the dealer, but we’re considering our next move if (as likely) it’s needed.

I cancelled the two ferry crossings we had booked today :(
 
Jul 28, 2008
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We got a pressure differential reading from them today - 100mBar, which is massive, and doesn’t seem to fit the 25% to me (Jane, I know Rog is better at the boy stuff).

As I said we’re in so deep cost-wise now it would be stupid to pull out with the dealer, but we’re considering our next move if (as likely) it’s needed.

I cancelled the two ferry crossings we had booked today :(
As I say, 25% is calculated and tech muppets will reset the calculation to get the light to go of ("there you are, fixed!"). 100mb at idle is too high and suggests blocked, (its not so high that it indicates iffy sensors). But easy to see if pressure increases with rpm etc, and if so really needs a clean (but Fiat can't do decent cleans, its easier to charge you £1000s for a new one.... But if the root issue as to why its blocked is not fixed, then the issue will reappear). If they try a forced regen that can overheat and crack blocked DPFs - but makes them sound clever..

Nope, new in 2019. 30k miles on the clock now.
Who has serviced it? If Fiat, or a Fiat Pro dealer, the ECU should've been updated ages ago to prevent this issue. Do you know if it was? (this is why I do ECU dumps pre/post service...)
 
Jan 27, 2018
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the1andonly I think we met at the Love Touring festival in '23 :)
4 blissful days parked next to the runway.
to your problem the service notes they are working to is attached. if they are working to a later one please try and get a copy even paper of anything they plan to do and part nos if poss.
Trying not make this too long not suceeding hope you understand

The percentage DPF mass value value as reported by diagnostics is misleading.
The reported states are:
  • between 0% and 30% (Particulate filter status: NOT CLOGGED)
  • between 30% and 120% (NORMAL CLOGGING)
  • between 120% and 200% (FILTER CLOGGED)
  • > 200% (TO BE REGENERATED)

What is an acceptable figure for DPF Differential Pressure (measured in mbar)? The answer is as little as possible. But if it flatlines at zero its dead.
Adding back pressure will make the engine work harder, and use more fuel to deliver the same power.
<20 Brilliant DPF causing almost no restriction
20-99 Good result and typical of a DPF in good working order
100-250 DPF causing up to 0.25 BAR of pressure – needs investigation
250-500 Serious restriction probably not allowing car to do a Forced Regen
500-1000 Performance loss very marked at this level
1000 Car can’t pull the proverbial skin off a rice pudding. All your boost is stuck in the DPF
these are under load 2000rm

My thoughts on the problem having an example to play with and analysing data from a lot of engines from around the world is that its related to poor design component deficiencies and poor software.

The problem is basicaly too much shit in the DPF and LPegr system Blocked Cooler primarily as a result of poor ecu programming dealing with over fueling/ poor air control

Poor design: the engine has a DPF and uses overfueling to enable Regeneration, world class would have 5th injector (fiat does use the 5th injector on some car and not others with same engine, space reasons). The Citroen Peugeot ad blu is also a problem with a 5th injector system trying to do two jobs DPF regen with diesel and SCR with adblu. The Ducato injectors are the same as earlier models but require more precise metering. The overfuelling with this injector can cause build up on the tips giving wider injector variances.The Fiat spec is +-2 mine and poor ones can be +-4. In comparison my VAG 1.6 is +-0.5. Hence regular dosing with injector cleaner.

Manufacturing defectsJohnson Mathey makes catalytic convertors and other precious metal products. JM designed the new type of DOC and DPF used in the new twin egr DPF. With my experiance of process engineering in coating ceramics i can easily understand batch related issues in the early production life.

Poor software: a number of updates have been available (not all FP dealers have been applying them at routine services. or not all Motorhomes get to see a Fiat Dealer at all.

The Problem generaly shows itself as a P0401 codes (sometimes with other codes). There is a "tea strainer"in the LPEGR cooler that get blocked, there is also a reduction in the temperature attained. The worst outcome can also be a cracked DPF. In its simplest incarnation it can be solved by Change of LPEGRcooler (8 hours Fiat time) and change of MAP sensor (counter intuitive and counter Fiat reccomendations).

My plan of action will be regular monitoring using Multiecuscan. and regular addition of diesel additives (current favourite Liqui Moly Diesel purge) and monitoring of the exhaust pipe (these should be spotless no soot). (I all ready have a replacement MAP and DPF sensor in the glovebox) and cooler in the shed. There are recorded instances from FF members of incorrect MAF sensors fitted at factory and incorrect injector numbers entered into ECU. The FIAT responce has varied dramaticaly across europe.
 

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Jan 27, 2018
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As I say, 25% is calculated and tech muppets will reset the calculation to get the light to go of ("there you are, fixed!"). 100mb at idle is too high and suggests blocked, (its not so high that it indicates iffy sensors). But easy to see if pressure increases with rpm etc, and if so really needs a clean (but Fiat can't do decent cleans, its easier to charge you £1000s for a new one.... But if the root issue as to why its blocked is not fixed, then the issue will reappear). If they try a forced regen that can overheat and crack blocked DPFs - but makes them sound clever..


Who has serviced it? If Fiat, or a Fiat Pro dealer, the ECU should've been updated ages ago to prevent this issue. Do you know if it was? (this is why I do ECU dumps pre/post service...)
100mb at idle is too high: yes absolutely
please dont allow a forced regen if its not cracked now soon will be Ducatos have a poor reputation on cracking after a forced regen if DPF not cleaned before hand.
Yes there are shedloads of low mileage motorhomes that have not been updated. V28 for a manual or V32 for comformatic is my minimum reccomendation. I was lucky in that my van was updated within 3000miles without my knowledge (at dealers for warrenty work and a recall).
I suggest you "waste 120 quid on Multiecuscan" and get data, what can it do ? it can help you make the right decissions and stop Fiat taking your pants down any more that necessary. Is the exhaust clean or sooty.
 
Jan 27, 2018
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(Did you buy 2nd hand? I fear many that have been serviced cheaply and sold on will have this problem and bite unsuspecting new owners :( )
Just had an email from a friend whos been helping someone on Faceache. the crux of the story is shes recently bought a 2016 Ducato been ripped off by a local garage and eventualy sorted by Fiat pro (at a cost including a new ecu). Its an example of what i expected to see a while back. a problem that no one can diagnose being hidden by software deletes then sell van on quick. Then some other poor sucker has to deal with it.

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Jul 28, 2008
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Just had an email from a friend whos been helping someone on Faceache. the crux of the story is shes recently bought a 2016 Ducato been ripped off by a local garage and eventualy sorted by Fiat pro (at a cost including a new ecu). Its an example of what i expected to see a while back. a problem that no one can diagnose being hidden by software deletes then sell van on quick. Then some other poor sucker has to deal with it.
:( Yep. Sad.
 

RedFrame

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Its the differential thats important - e.g. difference between pre and post - so depends what you read and where
A high reading (that increases with RPM) suggests blocked
A very low reading that doesn't change much with RPM suggests it could be fractured internally.
Non changing numbers or weird numbers, or not following RPM could suggest sensors.
As for the "known good" readings, see the fiat thread.
Also see example ducatos on the youtube channel I suggested.

Anyone who suggests forced DPF regens is a muppet generally, as there is a reason the DPF is blocked, and forcing a regen and resetting soot count looks good on the ECU data but does fk all. Also if there is an issue, a forced regen can cause more damage .....
Or you could read the Motorhome Fun thread....?


Cheers
Red.
 
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Jane And Rog

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As I say, 25% is calculated and tech muppets will reset the calculation to get the light to go of ("there you are, fixed!"). 100mb at idle is too high and suggests blocked, (its not so high that it indicates iffy sensors). But easy to see if pressure increases with rpm etc, and if so really needs a clean (but Fiat can't do decent cleans, its easier to charge you £1000s for a new one.... But if the root issue as to why its blocked is not fixed, then the issue will reappear). If they try a forced regen that can overheat and crack blocked DPFs - but makes them sound clever..


Who has serviced it? If Fiat, or a Fiat Pro dealer, the ECU should've been updated ages ago to prevent this issue. Do you know if it was? (this is why I do ECU dumps pre/post service...)

Thanks. Our first service at just over a year was with Fiat but that garage closed and then we moved to a local garage rather than go to Canterbury, long drive and more logistics issues if leaving the van. Hence the ECU was only updated this year, as the first thing Fiat tried to do to fix it.

Lesson learned though.
 
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Jane And Rog

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But easy to see if pressure increases with rpm etc, and if so really needs a clean (but Fiat can't do decent cleans, its easier to charge you £1000s for a new one....

I’m not sure if we can do that with our ODB, and we don’t have a Windows laptop to run the software everyone’s talking about on that thread. We do have an iPad - will that do the job if we buy that software for it?

As I said up thread, we’re committed to the new injectors, EGR and DPF now. The DPF should now be in the country in 10 days after Rog spoke to Fiat Italy.

Update: multiecuscan iOS will not export to CSV etc so I’ll have to find a PC. Maybe Parallels will work but the BT support worries me. That and the price of a windows license…

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