Technical Ducato P0401 P0402 P0236 P0238 and limp mode its 2017 Euro 6, EGR changed, What do I check next

[theoneandonly]

kangexpress said:
Hello everyone,

I'm back after a long break.

Those who know my story know that I invested a significant amount of money, which ultimately led to installing four new engines in my four Fiat Ducatos with the same engine model.

Now, after 300,000 km on the new engines, we're back to square one - the same problems start all over again.

We now know that we can monitor the LP EGR cooler temperature and airflow values.

I recently discovered a simple way to check if the problem is indeed the LP EGR cooler.

The temperature sensor is located between the LP EGR cooler and the LP EGR valve.

If the temperature sensor is removed from the pipe, the necessary airflow can be directed through the

And if it gets clogged again, I came up with a solution: replace the temperature sensor with a pipe hose and install a pipe that leads to the air filter housing. This will create a bypass for the LP EGR cooler, which may remain clogged.

Or could a cleaning fluid be put down this orifice. This assumes the fluid does not end up down the turbo.
@Fredastaire is this what you were after when you removed the battery box and couldnt get passed the comfortmatic bit. Would it work for a manual.

 

[Fredastaire]

@theoneandonly yes.
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I bought a LP EGR temp sensor( in case I bust mine), bought the gasket between the elbow and the LP EGR. Bought a screen wash pump/ pipe; a bowl, the caustic.....
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My plan was to undo the lower EGR ribbed flex pipe where it meets the silencer, cap the end with a lead disc. Remove the temp sensor, undo the elbow then pump in a measured amount of caustic to fill up the cooler+ flex pipe. Leave twenty minutes, drain out to my bowl. Repeat the process twice with fresh water.
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I got caught out with two problems. First although I can see the temp probe connector I can't reach it. My gearbox is comfortmatic so the gubbins prevents access, even a two year olds hands couldn't reach it. I think top access by removing the air cleaner and MAF inc pipes might allow. The second problem was a bad back which stopped all play.
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I got my garage to fit my second new cooler instead.
I've probably got another 2 years before it reoccurs.
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I seriously want to explore the thought of adding a resistance to the engine harness sensor wires to make the software 'not open' or minimize the LP flap.
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I need a second hand engine harness to examine, alas they are expensive on eBay.
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If you have a manual box then I suspect you can reach the sensor plug/ socket readily.
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So guys, who is going to try....

 

[theoneandonly]

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So guys, who is going to try....

Thanks for reminding us. I think a modified temp sensor holder/ corner with both sensor and pipe to filter housing (initialy blocked off) for the next change of cooler may be sensible if someone is to go down the not replace the dpf. There are a couple of people that have followed this route unfortunately one has had only 6 months out of it.

 

[Fredastaire]

A number of you know im the originator of this long running post and that ive survived so far by replacing the LP EGR Cooler, now for a second time.

I still want to find a long term solution that avoids the terribly expensive new DPF.

You will also know that ive been looking at ways to disable or reduce the effect of the LP EGR. I wondering about adding a resistor to the temperature probe such that the software thinks that hot exhaust is passing to the turbo inlet and it needs to close or partially close the LP EGR ‘exhaust in’ flap. This would prevent the full flap opening which in turn closes the ‘clean air’ butterfly thus strangling an engine if the cooler is blocked by soot.

I bought a new temp sensor from Fiat then did some tests with my trusty voltmeter.



Iced water 2 1/2 degrees c gives 31.25 K ohms

Ambient 20 degrees gives 23 K ohms

Stirred boiled water in mug 78 degrees gives 5.5 K ohms.

..

AS I cannot reach the probe electric connector, I'm thinking of opening up the engine harness to locate the sensor wires (2), then soldering a pair of wires to them and up in the engine bay using a terminal block, (in a box) this allows adding a resistor in parallel. @theoneandonly suggests to try starting with 15k which at 40c will con ecu to thinking 70c. its guesswork and would no doubt need alternative value resistors and see the effect on multiecuscan.



Three things stopped me, first I had a bad back, second I have Comfortmatic and cannot reach the temp probe harness connector, I( can see it but cannot get at it due to the gearchange servos), third I cant locate a wiring diagram to give wire colours.



Any comments anybody?

 

[deejays]

A number of you know im the originator of this long running post and that ive survived so far by replacing the LP EGR Cooler, now for a second time.

I still want to find a long term solution that avoids the terribly expensive new DPF.

You will also know that ive been looking at ways to disable or reduce the effect of the LP EGR. I wondering about adding a resistor to the temperature probe such that the software thinks that hot exhaust is passing to the turbo inlet and it needs to close or partially close the LP EGR ‘exhaust in’ flap. This would prevent the full flap opening which in turn closes the ‘clean air’ butterfly thus strangling an engine if the cooler is blocked by soot.

I bought a new temp sensor from Fiat then did some tests with my trusty voltmeter.



Iced water 2 1/2 degrees c gives 31.25 K ohms

Ambient 20 degrees gives 23 K ohms

Stirred boiled water in mug 78 degrees gives 5.5 K ohms.

..

AS I cannot reach the probe electric connector, I'm thinking of opening up the engine harness to locate the sensor wires (2), then soldering a pair of wires to them and up in the engine bay using a terminal block, (in a box) this allows adding a resistor in parallel. @theoneandonly suggests to try starting with 15k which at 40c will con ecu to thinking 70c. its guesswork and would no doubt need alternative value resistors and see the effect on multiecuscan.



Three things stopped me, first I had a bad back, second I have Comfortmatic and cannot reach the temp probe harness connector, I( can see it but cannot get at it due to the gearchange servos), third I cant locate a wiring diagram to give wire colours.



Any comments anybody?

Hi @Fredastaire , back on page 63, @Sillystu84 provided two photos of the temp sensor, including the actual wiring harness wires. Perhaps now you know the value of the resistance, it may be a relatively simple matter of disconnecting battery, then ECU plugs and use your trusty multimeter to confirm the wiring once you have located the correct colour wires. One lead would most likely be at earth potential, the other would be the reference resistance. Hope this helps. Cheers, Daryl.

 

[BoultsG]

Oh dear, 14 months on and our P0401 has returned. We replaced our LP EGR Cooler on Nov 23 and have covered almost 15k. These past few weeks we have received an intermittent P0401. @theoneandonly I have attached a couple of MES files from this morning's journey. Could you please take a look and let me know your thoughts.

 

[Fredastaire]

The figures say it all. Actual airflow is 1/3 of desired. The LP EGR is fully open at circa 4.8, (can't read the actual figure whilst typing).
The engine is strangled by the cooler blocking with soot and the LP EGR opening fully whereby it cuts off the clean air from the air filter.
It's like putting a scarf around somebody's neck and pulling it tight, they would also protest at being unable to breath!!!!!
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Conclusion - the cooler needs removing for caustic cleaning before refitting.

 

[CheeseMonster]

If I compare @BoultsG results to those from my own 2017 twin EGR van I would question the difference between Boost Pressure and Desired Boost Pressure. If the actual boost pressure is lower than the desired boost pressure there may be a air leak. Less air than the expected would result in a rich mixture. I would carryout a smoke test to look for leaks. Watch http://www.youtube.com/@ORileysAutos

 

[theoneandonly]

The lpegr is not under control and is jumping from fully open to fully closed. The lpegr temperature is also low.
These are signs that the lpegr cooler is blocked. time to reclean.

The Air intake % of desired at 30.1% is typical of restrictive breathing as seen with a blocked cooler.
If there was a leak in the turbo system I would expect the difference to be one way ie actual always lower, this is not the case as is evident in the 2 graphs.

 

[CheeseMonster]

@theoneandonly
Just me thinking out loud but if the egr cooler gets blocked it's because the DPF isn't catching enough particulate matter.

Question 1: So is the DPF not up to the job?

Question 2: Is there a particulate matter sensor prior to the DPF?

@theoneandonly thanks in advance for answers to questions 1 & 2.

 

[Fredastaire]

@CheeseMonster It's because the DPF has been internally heat damaged by excess burn temperature during the repeated regen burns on the earlier software.
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It would seem that Fiat reacted to failures and updated the software to versions 28 and 32.
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Again it seems that injectors also got damaged by the earlier software issues with some engines.
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And yet......
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There are plenty of our model Ducatos with updated software that are well alive and kicking AND doing tremendous mileages.
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Maybe the early production runs of the DPF had production quality issues.
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I'm on my second cooler change and expecting it to last 10-15 thousand miles before it too will be soot blocked.

 

[Fredastaire]

Please be aware that we help each other on here for free.
For any newcomers here we know exactly what the problem is. The details are all on this post for anybody to read.
The main cure is known in that you need at minimum a new DPF and caustic clean the LP EGR cooler.
There are options detailed to destroy and remove the DPF internals, followed by software delete of both egrs. Some members have had this done successfully, others have failed. For the UK it's illegal, further there are reports in the press that the MOT may yet include the tester to look for emissions tampering resulting in a fail
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The lowest cost option is to remove and clean the LP EGR cooler and accept to repeat every circa 15,000 miles. This is my current choice.
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I do have in mind an option to reduce the LP EGR max opening, however it's still theory presently.

 

[BoultsG]

@theoneandonly, @Fredastaire; there has been an awful lot of research/ temporary fixes, etc with regards to the P0401/P0402 since @Fredastaire started this thread back in 2021. Are you aware if anyone in the UK has challenged Fiat? With all the current evidence there must be cause for some sort of redress.

 

[Serrow225]

@theoneandonly, @Fredastaire; there has been an awful lot of research/ temporary fixes, etc with regards to the P0401/P0402 since @Fredastaire started this thread back in 2012. Are you aware if anyone in the UK has challenged Fiat? With all the current evidence there must be cause for some sort of redress.

Hi,think the problem is the commercial vans got sorted under warranty as they got dealer 1st service very soon as problem was found within warranty time and the motorhomes as, I suspect like my van it missed it's dealer 1st service plus low usage ment it missed any fait warranty repair by the time the 401 etc happened it was to late.

 

[theoneandonly]

@theoneandonly, @Fredastaire; there has been an awful lot of research/ temporary fixes, etc with regards to the P0401/P0402 since @Fredastaire started this thread back in 2021. Are you aware if anyone in the UK has challenged Fiat? With all the current evidence there must be cause for some sort of redress.

Yes Fiat has been challenged. the first success i know of was from a member here and he went for the Italian CEO on social media and got his case resolved. He even had a technician come over from Italy to monitor the repairs (2nd time). I also know (via Motorhome fun) of at least 4 that have had Fiat involvement. Normaly in the way of components gratis but paying for labour, these were all out of warrenty. deep details of the circumstances of each case is not known (what may be relevant is some Fiat pro history see last 2 sentances). What is certain is if there has been no Fiat pro history there will be no Fiat intervention.

Hi,think the problem is the commercial vans got sorted under warranty as they got dealer 1st service very soon as problem was found within warranty time and the motorhomes as, I suspect like my van it missed it's dealer 1st service plus low usage ment it missed any fait warranty repair by the time the 401 etc happened it was to late.

I think this is absolutely the case and there are still low milage examples turning up and catching new owners unaware though with "education posts" here on faceache and a number of motorhome forums we have been able to make at least a few make the right decisions and not get ripped off or buy a good example. By we it is mainly FredAstaire. Although the Majority of Motor homes may have had first 2yr service outside of the Fiat pro network it is believed that during this period a number of dealers wern't automatically updating ECUs. It could be a coincidence that the dealer pro Network isn't as large as it once was.

 

[proppb]

Hi All this may be of interest.

 

[deejays]

Please be aware that we help each other on here for free.
For any newcomers here we know exactly what the problem is. The details are all on this post for anybody to read.
The main cure is known in that you need at minimum a new DPF and caustic clean the LP EGR cooler.
There are options detailed to destroy and remove the DPF internals, followed by software delete of both egrs. Some members have had this done successfully, others have failed. For the UK it's illegal, further there are reports in the press that the MOT may yet include the tester to look for emissions tampering resulting in a fail
.
The lowest cost option is to remove and clean the LP EGR cooler and accept to repeat every circa 15,000 miles. This is my current choice.
.
I do have in mind an option to reduce the LP EGR max opening, however it's still theory presently.

Hi @Fredastaire , if you are still considering the LPEGR temperature sensor, according to recent reported events it may well be that the sensor is connected to P32 and P48 of connector A of the ECU, with P48 at ground reference and the varying signal on P32.

 

[Fredastaire]

Hi @deejays yes I'm still wanting to investigate a temp sensor override for the LP EGR. Late last year I was planning to insitu clean the cooler but got stopped by a bad back and being unable to reach the temp sensor plug / socket location. (It's well hidden by the comfortmatic operating hydraulics). Because of early signs of the cooler blocking I decided to have my cooler changed whilst the van was having its annual MOT. Thus I'm in no panic to do anything.
I guess now I have to find the harness connector for those pins. I wonder if I need to remove the left headlight to access the ECU box. Any ideas?
.
In case you are wondering about how I began my recent comments about ' helping each other without charge'; we had another post on here from a suspected scammer who appeared again (slightly different id I think), proffering a solution for which he wanted money. Our admin team has kindly removed his message again.
.
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How did you locate those plug pin numbers? Have you a wiring diagram?
.

 

[deejays]

Hi @deejays yes I'm still wanting to investigate a temp sensor override for the LP EGR. Late last year I was planning to insitu clean the cooler but got stopped by a bad back and being unable to reach the temp sensor plug / socket location. (It's well hidden by the comfortmatic operating hydraulics). Because of early signs of the cooler blocking I decided to have my cooler changed whilst the van was having its annual MOT. Thus I'm in no panic to do anything.
I guess now I have to find the harness connector for those pins. I wonder if I need to remove the left headlight to access the ECU box. Any ideas?
.
In case you are wondering about how I began my recent comments about ' helping each other without charge'; we had another post on here from a suspected scammer who appeared again (slightly different id I think), proffering a solution for which he wanted money. Our admin team has kindly removed his message again.
.
.
How did you locate those plug pin numbers? Have you a wiring diagram?
.

Suggest you refer to this recent post: https://www.fiatforum.com/threads/elearn-all-fiats-including-ducato-euro-6.513989/unread

 

[theoneandonly]

Hi @Fredastaire , if you are still considering the LPEGR temperature sensor, according to recent reported events it may well be that the sensor is connected to P32 and P48 of connector A of the ECU, with P48 at ground reference and the varying signal on P32.

Ive been tying to find this, E5050 but cant find the component identifier (eg k046 rpm/ crankshaft sensor) or P32.
ps just come back from specavers with new glasses.