OM 651 in regen loop

[tpn]

I have a 2012 204 Estate. Some time ago I hit a bad patch on a country road and the eml came on and car went into limp mode. Long story short the second bolt on the bottom of the inlet manifold snapped-I found it in the tray.
I knocked off the light with an Icarsoft MB11 and once I did not accelerate quickly the light and limp mode stayed off.

On a trip from Liverpool to the Cotswolds I noticed that the Icarsoft showed a P245328 fault "Soot content not OK mechanical fault."
It was showing a 400% fill and 3g soot. I did a driving regen and it brought the fill down to 0 and created 3g ash.

It then started passive regen very often but the fill content never reduced below 10%.

I recently put in a new inlet manifold, cleaned the EGR, put in a new thermostat, and diesel filter housing. No fault codes and no limp mode. Driving perfect.

Took it on short trips for a day or two without a problem, then yesterday after a 40 mile trip I noticed on the Icarsoft the following two faults. (no limp mode and no light on)
P246309 Soot content not OK, mechanical fault. Content was 283%. Soot 6g. P245328 "input for differential pressure sensor 1 in the DPF has a malfunction, invalid signal"

I was parked at this stage so decided to leave it until this morning.

This morning the Fill level had gone back down to 92% even before it was started. Took it for a drive, it did a passive regen at 100% but brought the fill down to 10% only and 2g of soot.
It then increased quickly to 60%, then suddenly dropped down to 40%, then did a passive regen again, this time to 20% fill.

No codes, no limp mode, back pressure etc within allowances. Only thing I noticed that may not be correct is that the B28/5 Pressure Sensor downstream of air filter stays constant at 1.00 bar. Any experienced ideas. oh, and the injectors appear to be ok also.
I am thinking of changing the Differential Pressure switch

 

[onefortheroad]

B28 should be within + 0.04 to - 0.04 .

 

[mattkh]

If this differential pressure sensor is easy to get to and remove, then I would clean the sensor and test.

 

[tpn]

The differential sensor is easy enough to get to, but it is not a sensor that can be cleaned, it is a sealed unit. The tubes can get blocked, though and I will be examining that next.

 

[tpn]

B28 should be within + 0.04 to - 0.04 .

Are you referring to the B28/5? Is that at tick over or under load?

 

[mattkh]

The differential sensor is easy enough to get to, but it is not a sensor that can be cleaned, it is a sealed unit. The tubes can get blocked, though and I will be examining that next.

Thanks.
A request. Please take a picture if possible.

 

[Dean Fletcher]

Are you referring to the B28/5? Is that at tick over or under load?

This is at idle

 

[tpn]

Thanks.
A request. Please take a picture if possible.

I have not taken the original off yet https://www.amazon.co.uk/Bosch-281-...83&hvtargid=pla-464550716310&psc=1&th=1&psc=1, but this is similar to the replacement that I have

 

[Dean Fletcher]

I have not taken the original off yet https://www.amazon.co.uk/Bosch-281-...83&hvtargid=pla-464550716310&psc=1&th=1&psc=1, but this is similar to the replacement that I have

Not a bad job really.

 

[tpn]

So I finally got this sorted out and the DPF problems did not have anything to do with the inlet manifold leak. It was just a coincidence.
A 400% fill issue is very very likely an incorrect reading flagged by a failing Differential Pressure Sensor. The tubes need to be checked also and flushed with compressed air, just in case.
If your B60 back pressure readings are within the limits -0.945 to 1.545 at idle; 3.465 to 4.065 B at 3000rpm- your DPF it not blocked.

The diagnostics only flagged the P245328 fault (input for differential Pressure Sensor 1 in the DPF has a malfunction, invalid signal) once, so it could well slip under the radar for the rest of the tests.
To add to the confusion the Icarsoft MB V11 has a section under the driving regeneration, whereby if there is a "soot content not OK" fault where it is too high for a regen, it will lead you into a diagnostic programme, whereby it will assess the true content. If you do not go through with a driving regen and you do not come out of the programme correctly it will throw up the fault again; this time with a fill reading of 356g and a soot content of 13g. (I have checked this four times, each time with the same results.

I also found that the new Differential Pressure Sensor was not recognised, so I used a Snap On to tell the system that a new DPF was fitted. It reset everything to zero and accepted the Differential Pressure Sensor.

A 100 mile drive saw the fill go up at 1% per mile (this was its pre problem norm) and at 100% the B19/11 climbed to 680c to 700c and the passive regen was completed in approx 5 miles (no need for increased revs etc for a passive regen, it will do it at normal driving).

All is ok now..at least for the moment.

 

[M80]

If you're car is going into regen after 100 miles I would suggest there is still a problem.

Same engine I'm seeing regens between 460 - 560 miles. Like yours it completes between 6 - 10 miles.

The advantage of increasing revs, well engine load would do it, the increased exhaust flow increases the temperature.
On Wednesday mine kicked it while sat in a road work queue, a bummer as I had been travelling nicely over the previous 100 miles.
Anyway the temperatures were struggling to pass 500. Driving slowly through Macclesfield in traffic I dropped gears to increase revs, keeping the temps at around 600 (I believe) aids incineration. The latter 3 miles were while hauling up the Cat & Fiddle road, steep and twisty. Temps were 700 and above regularly.

 

[alexanderfoti]

400% is not a direct reading from the differential pressure sensor. It's is calculated full level from exhaust back pressure, differential pressure, boost level and calculated airflow (maf).

The fill level will vary from 1% to around 250% in normal driving. When it reaches 400% the car will log a fault and stop carrying out regens.

When fitting a new differential pressure sensor, the dpf fill level needs to be taught in, which involves a high idle for 15+ minutes. If you have just reset all values to 0 then the fill level will rise much quicker and if too quick, it will log another fault code (there is a component fault).

I would keep a close eye on it but eventually that inlet manifold will cause an issue.

 

[tpn]

If you're car is going into regen after 100 miles I would suggest there is still a problem.

Same engine I'm seeing regens between 460 - 560 miles. Like yours it completes between 6 - 10 miles.

The advantage of increasing revs, well engine load would do it, the increased exhaust flow increases the temperature.
On Wednesday mine kicked it while sat in a road work queue, a bummer as I had been travelling nicely over the previous 100 miles.
Anyway the temperatures were struggling to pass 500. Driving slowly through Macclesfield in traffic I dropped gears to increase revs, keeping the temps at around 600 (I believe) aids incineration. The latter 3 miles were while hauling up the Cat & Fiddle road, steep and twisty. Temps were 700 and above regularly.

There are three types of regen: 1 a passive regen, you will not know it is happening and there is no increase of revs etc required or provided.

2 an active regen which will usually happen when the passive regen has failed several times which requires ECU intervention.

3 the forced regen where you tell the system to regen.

Active and forced regens are best if they are not happening often. The excess diesel can contaminate the engine oil (it has led to premature engine failures, especially in the Mazda 6).
My car, has from new, done passive regens every 100 miles and it has kept the DPF in excellent condition.

Apparently the timing of the passive regen can differ from manufacture year to year and the designation of the particular engine.
Mine is a Blue efficiency-not to be confused with a Blue tec/ad blue system.

 

[tpn]

400% is not a direct reading from the differential pressure sensor. It's is calculated full level from exhaust back pressure, differential pressure, boost level and calculated airflow (maf).

The fill level will vary from 1% to around 250% in normal driving. When it reaches 400% the car will log a fault and stop carrying out regens.

When fitting a new differential pressure sensor, the dpf fill level needs to be taught in, which involves a high idle for 15+ minutes. If you have just reset all values to 0 then the fill level will rise much quicker and if too quick, it will log another fault code (there is a component fault).

I would keep a close eye on it but eventually that inlet manifold will cause an issue.

My fill level will never exceed 100% and on other car issues that I have looked at the 400% is a reading that is originated by the DPS failing.
At 400% my car did not have a fault code, mil light or a limp mode. Its back pressure was well within the parameters.
It is impossible that it had a 400% fill with correct back pressure.
Also the DPS had an intermittent fault-probably the diaphragm- and while working it was showing 0.01 bar on the B28/8.
again impossible if the DPF was at 400% fill.
The MB V11 showed, in the pre forced regen programme, that the true reading was 0.26 fill and 0 soot.
It is presently filling at the normal 1% per mile.
But, of course, a day is a long time.

 

[alexanderfoti]

Just my 2p

 

[tpn]

Just my 2p

I greatly appreciate every input, that is what these forums are for. I tend to do huge research each time I encounter a problem, but being a tad lazy at times I always steer towards the forums at first. Saves a lot of time if someone else had encountered and solved the particular problem.
I should have elaborated on my above statement re 1% per 1 mile. This is at 45mph and returning 62 mpg.
Obviously time is a factor also and at 60mph I have noted a 3% increase in 7 miles, so that is 1% in 2.3 miles o0n those occasions.

 

[supernoodle]

Apparently the timing of the passive regen can differ from manufacture year to year and the designation of the particular engine.

That's not passive then. The word passive would imply no ECU intervention. So the engine is in a normal operating mode and you happen to be pushing it so hard the exhaust gets hot enough to regen. Apart from on the Autobahn, not sure where this would happen.

Active is when the ECU intentionally tries to force a regen through changes to timing, fuelling, airflow etc to keep the exhaust temperatures elevated. This is the norm.

 

[tpn]

That's not passive then. The word passive would imply no ECU intervention. So the engine is in a normal operating mode and you happen to be pushing it so hard the exhaust gets hot enough to regen. Apart from on the Autobahn, not sure where this would happen.

Active is when the ECU intentionally tries to force a regen through changes to timing, fuelling, airflow etc to keep the exhaust temperatures elevated. This is the norm.

I get the passive regen every 100% fill. An active regen is, as I said elsewhere on this thread, with ECU intervention and when the passive regen has failed several times. There is no need for an active regen when the passive regen does the job.
The passive regen has to depend on the reception of certain signals.
Active regen will raise the fuel consumption, the revs, for starters, so the fuel consumption will drop and if it is getting an active regen every 100 miles the oil level would increase due to diesel getting into the sump and the quality of the oil would decrease.

Off the small screen of my mobile and on the big screen now. Hard to keep continuity on the mobile as the previous sentences are not visible as you type...anyway.
I should also have said in my previous post that after changing the Differential sensor I put in a can of JML re gen into the tank as this brings up the temperature for my first run. I then refuelled and did a further 100 miles where I monitored the fill going from 100% to zero. I did not monitor the temperature then but I assume that it has to be a passive regen as there was no reason for an active regen.

 

[tpn]

I get the passive regen every 100% fill. An active regen is, as I said elsewhere on this thread, with ECU intervention and when the passive regen has failed several times. There is no need for an active regen when the passive regen does the job.
The passive regen has to depend on the reception of certain signals.
Active regen will raise the fuel consumption, the revs, for starters, so the fuel consumption will drop and if it is getting an active regen every 100 miles the oil level would increase due to diesel getting into the sump and the quality of the oil would decrease.

Off the small screen of my mobile and on the big screen now. Hard to keep continuity on the mobile as the previous sentences are not visible as you type...anyway.
I should also have said in my previous post that after changing the Differential sensor I put in a can of JML re gen into the tank as this brings up the temperature for my first run. I then refuelled and did a further 100 miles where I monitored the fill going from 100% to zero. I did not monitor the temperature then but I assume that it has to be a passive regen as there was no reason for an active regen.

I guess I should have added that perhaps Mercedes give the "passive" regen a little help, but this 100 mile/100%, or 200 mile 100% removal of the fill level and the soot content is not noticeable and it is not recorded as a correction of Ash.
I have monitored many of these "passive" regens and fuel consumption remains as it was, revs do not increase and coolant temperature does not increase noticeably.
Whereby. when it does an "active" regen, all of the above are altered and you know that it is doing it; The diagnostics also flag the mileage that this occurred at.
I have looked at lots and lots of discussions on this subject and many Mercedes drivers have noted the 100/200 mile regen.

 

[tpn]

Thanks.
A request. Please take a picture if possible.

As requested pic of Differential Pressure Sensor

Thanks.
A request. Please take a picture if possible.

Differential Pressure Sensor as requested