P1206. Failed forced regeneration. Doblo 1.9. Help needed!!

[Poperon]

This is also posted on the Doblo forum.

It's a long, long story!

The very shortened version is:

A few years ago error code P1206.

A lot of reading up, research, checking forums and asking friends about how to fix this.

Error code comes up, I do something (mostly by replacement), a forced regen and then clear the error code. Back on the road for a few months maybe a year then P1206 returns and I have to find some other thing to do which might fix it, and so on.


This is what I've done:

Made a few graphs using MES

Changed the oil and reset the oil counter.

Replaced:

DPF pressure sensor

EGR valve

DPF

MAP sensor

The latest was replacement of the thermostat and engine temperature sensor.


BUT THIS TIME

The forced regen failed and it won't do it.

So, over to you knowledgeable folk.

What is going on?

What on earth have I got to do to fix

1. The P1206 problem
2. Getting the forced regen done so that I can get back on the road and see if this was the cause of the error code.

Any help much appreciated.

Ron

 

[bugsymike]

I don't know about MES, but on a 2012 C3 Picasso 1.6 diesel with 212k miles at the time it was chucking out unbreathable white smoke as it tried to Regen, I removed it and thoroughly cleaned it, told the ECU it was new and it ran another 3+ years before Eloys fluid ran low which I replaced and finally DPF had to be replaced. In fairness it did look quite clogged, when you removed yours last time was it visible clogged?
The point I am making is mine had spent a lot of it's life as a mini cab I think doing short slow journeys and rarely getting fully warmed up to clean it's self,
unfortunately this is something most of us do, but modern diesels don't like due to their designed emissions set up making them unsuitable for modern stop start journeys unlike older designed diesels.
I am wondering whether to start using DPF cleaner additive to to the fuel, much as in the same way I had to tell my daughter to use turbo cleaner for her VW Golf 130Hp GTD as the varaiable vane turbo kept clogging up and causing the car to go into limp mode.
Regarding your 06 Doblo 1.9, I had a 55 plate Doblo 1.9, 7 seater pre DPF with similar mileage and did the same driving as the Citroen with no issues in 4 years apart from a Crank shaft position sensor and sold it still running at 230K miles.
If yours burns oil or runs rich even a little, this along with short journeys may be a contributory factor.
As I said about not familiar with MES I was able to use a friends Snap On tool, but when the cinder count or amount of blockage reaches a certain point then the ECU prevents doing a Regen.
I assume you are using the correct "low ash " engine oil for your, I also change the oil more often than recommended along with an engine flush treatment at the time, although I know some cars and people don't recommend it.

 

[Poperon]

Hi Mike,

Thanks.
Oil is the Selenia one that Fiat recommend.

DPF is about 1000 miles old, but now needs regeneration. Once the P1206 error comes up it won't do a normal regen and requires a forced one, then the P1206 error can be cleared. I've got the dreaded P1206 but it won't do the forced regen (yet).

This morning I connected up MES and ran through the "Parameters" to see if I could spot something. The only thing that jumped out at me was the "Clutch Pedal" was showing "Pressed". Put my foot on/off the pedal and it changed to "Released". This makes me think that for MES to get the forced regen done the pedal must be "Released" otherwise it looks like you are about to put the car into gear and zoom off whilst it's doing its regen! Possible sticky clutch pedal sensor? Are there other conditions that need to met?

Cheers

Ron

 

[jackwhoo]

The clutch pedal pressed or released on mes only showing correctly after pedal pressed appears to be normal for mes......strangely yesterday I spotted exactly the same thing on multipla.


Does your pressure differential pressure read zero with engine not running?

Can you do a forced regen using the pedals like the 1.3 doblo?

 

[jackwhoo]

Hi,

How much fuel showing on gauge?

Engine temp over 70degrees c before attempt regen?

Before attempting regen check using mes clutch pedal shows released.

Best wishes
J

 

[Poperon]

Hi,

The differential pressure sensor (6 months old) reads 0 when off and looks to work fine.
Plenty of diesel in the tank and temp over 85°C.

Of course you disconnect the battery before replacing the thermostat and then you reconnect it before testing etc, well, it seems that on MES after reconnecting the battery the clutch position defaults to "Pressed" until you press it again and then shows the actual state of the pedal.
Does MES think your foot is on the pedal and therefore refuses to allow the forced regen to start?

Tomorrow is the earliest I can check this out and hopefully it'll do the regen!

Thanks

Ron

 

[jackwhoo]

Asked about fuel level because some vehicles will not regen unless fuel over a set level.

I think looking at parameters to make sure clutch pedal showing released them attempting a regen is a good idea.

Good luck

Let us know

 

[jackwhoo]

On multipla yesterday pedal showed pressed until pedal was depressed and released , then it showed released- battery had not been disconnected before hand.

 

[AndyRKett]

I think @bugsymike hit a valid point above, Are you doing long enough Journeys. The DPF needs to be run for a good amount of time to Regen. Therefore if the Car is trying to Regen and you stop and park up, you're preventing the system in place meant to keep the DPF clear from working.

We are an all diesel household but then every journey we make is 20+ miles because of living in a rural location, so the engine always gets up to temperature and as a result in the 90k that I have done in my Golf since new, it has only done a regen once. The regen is done because lots of slow driving or short journeys will cause it to clog quicker. So if you have replaced the DPF and the pressure sensor and its still throwing up issues with failed Regens then I'd assume you don't do lots of particularly long or particularly fast trips.

What you may need is what we used to call an Italian tune up, a nice long drive at speed, get the exhaust nice and hot to burn off all the particular matter that builds up in the DPF, this will help even without a Regen.

The forced Regen might be failing for a number of reasons, one of them could be the filter is already too clogged if the car is only doing short journeys all the time.

 

[Poperon]

Hi,

Regen worked ok...but...

Problem still not fixed. Here's an update.

Somehow, I found on the internet a Fiat service news sheet about fixing this damn P1206. https://manualzz.com/doc/6412115/operation

First on the list was to check that the thermostat was working ok. It wasn't, sticking open with temperature below 80C.

Replaced the thermostat and thought this could have been the problem all along...no...got the P1206 again, yesterday.

From this service sheet this is the list of things to look at for a P1206:
1 - Incorrect thermostat operation
2 - Incorrect flow meter reading
3 - Incorrect injection operation
4 - Presence of oil in intake circuit
5 - Turbo compressor problems
6 - EGR value problems
7 - Condensation
8 - Oil leakage from valve guides

1,2,3,6,7 checked ok. This leaves 4,5 and 8.

The front runners are ok and the remainder seem unlikely.

Any ideas much appreciated.

Thanks

Ron

 

[bugsymike]

I am not an MES user so maybe others can comment better, however is there any relevance, in readings for boost pressure being higher than desired boost pressure? I see it mentions only 30% particulate blocking and normal clogging, but could a partially blocked DPF affect turbo readings? What was the mileage when you changed the original DPF previously assuming driving conditions similar? Is there another thing that can cause the discrepancy or is that amount of pressure difference normal?
Another thing that may be totally irrelevant and I don't want to steer you down a wrong path,is something I mentioned on a recent Ducato thread, I was chatting to a retired Fiat camper van mechanic he said one of the most common things they changed first was the DPF pressure sensors due to a high failure rate.

 

[jackwhoo]

Dpf 1000miles old - was that a new dpf? Or used dpf?
If new which manufacturer?

I think bugsy has a point about pressure sensor- if it's not the sensor and the the ecu is receiving the correct pressure reading then the dpf may be obstructed- that would be very unusual with a new dpf of decent make after only 1000miles.

Did you tell the eve a new dpf was fitted using mes?
You could try completing a regeneration and then telling ecu new dpf fitted again as this could reset parameters successfully

 

[Poperon]

Hi and many thanks,

I'd looked at the boost pressure discrepancy and wondered if the fairly small difference was significant. Any ideas?

The dpf is 30% blocked and the differential pressure reading is low, this blocking figure tallies with mileage since dpf was replaced/regenerated.
The DPF is about 1000 miles old and to get it to do a regen after the foot brake business (see above) I had to tell ecu that a new DPF was fitted (again). Regened ok then.

Differential pressure sensor replaced a few thousand miles ago (genuine part).

DPF was new from BM Catalysts. It fits ok and has an Homologation certificate, which I think means it's been certified to do the same function as the original part.

ECU told about the new DPF (MES), BM Catalysts require that a forced regen is completed when the new DPF is fitted (this was done).

This is all baffling.

Any more suggestions very much appreciated.

Ron

 

[jackwhoo]

Something is causing a high differential pressure reading at ecu.
Check pressure sensor wiring and connectors.
Is it possible the recent dpf pressure sensor faulty?
Other than that I have no further ideas.

 

[Poperon]

Hi,

The Fiat Service News Sheet which I refer to earlier is quite an in depth look at DPFs how they work etc (pages 61 onwards) and also a section on the P1206.
One would think a regen should be only to do with differential pressure readings, triggering a regen when the pressure difference has exceeded a given level. But the service sheet says that other criteria need to be met before a regen in even considered (page 77) ie:

Thermostat "Incorrect operation of the thermostat (including excessive opening and closing tolerances) causes a high production of
smokiness (causes a different calibration of the reference threshold in the engine ECU: approximately 88° C): this
causes incorrect calculation (rounded down of the amount of PM collected in the DPF.
This amount of particulate in excess not calculated by the ECU causes incoherence between the percentage calculated
by CCM and the back pressure in exhaust. This causes the engine warning light (MIL) to light up"

Many thanks

Ron

 

[bugsymike]

Thermostat "Incorrect operation of the thermostat (including excessive opening and closing tolerances) causes a high production of
smokiness (causes a different calibration of the reference threshold in the engine ECU: approximately 88° C): this

Is that "Fiat Talk" for short stop/start journeys, or in other words the sort of use many smaller diesels are bought for in the first place, in the past.