W204 DPF Warning Light???

[Tuercas viejas]

Forgive me of this sounds like a stupid question, and it will if you know the answer...

Someone earlier in the thread asserted that their car performed a regeneration every thousand miles on their way to work.

Is the EMS programmed to do the regeneration as the mileage reaches each thousand miles or does the dpf sensor trigger a regen?

Les

Les
The DPF is connected to a sensor by two S/S tubes one fore and one aft of the DPF.
Its called the differential pressure sensor--Looks like a rectangular box like sensor with two V connector tube al la Churchill salute!
Its a piezo acting sensor so there is no actual exhaust gas going through it.

That pressure difference communicated with the PCM combined with exhaust temp sensors plus a few other things triggers a re-gen. These temperatures easily get to 500c in an instant when the re-gen starts and it will shut down if the gas temp gets to about 1800 c!

Always take into account that the SOC cat & DPF requires input temperatures to make the whole system clean itself out.
If your thermostat is not letting the top pipe engine temp get to at least 83c you are on the road to no regen, as is an active engine fault code stored in the PCM.

Remember heat is your friend the other is the oil you use. With these exhaust gas temps the engine lube oil is getting taxed to the max. The vapours being given off tend to plug up the DPF more than normal sometimes as well.

By the way the MB scan system isn't the Holy Grail in all this there are others (scanners ) that will show all this stuff like Snap ON as mentioned previously.

All the best
Tuercas Viejas

 

[garycat]

This may be a silly question but how does the ECU know that you're not going to reach the end of your journey as soon as the regen starts if it takes about 20 mins to do it?

Does it have to run a full cycle to completion for it to be effective?

 

[Mr Filipov]

This may be a silly question but how does the ECU know that you're not going to reach the end of your journey as soon as the regen starts if it takes about 20 mins to do it?

Does it have to run a full cycle to completion for it to be effective?

Well it doesn't. Ideally if you can run till it's complete then happy days. If not, there is a safety net, which is that it will resume the regen next time the conditions are met.

 

[lgm63]

Many thanks for all replies, very much appreciated

 

[Mgbond]

Regen Fail

I have engine light on and code is P244A. Something to do with DPF. A couple of weeks ago I had a boost leak but couldn't get it in to the dealer straight away (was the classics split intercooler pipe) so had to drive it like that for a bit and I did reset ecu a few times. You could see when the ecu was trying to work out what was wrong by puffs of black soot out the back. That was fixed and now I get this. I was thinking it was the previous issue that's blocked DPF?

Once reset it comes back at different times. Tonight I tried to keep revels between 2k-2.5k and every time I did this it would after a short time go into limp mode. So then I tried keeping revs above 3k and it nver went into limp mode.

So in this case I'm thinking that it's the regeneration that is causing the limp mode. If DPF is so blocked can it cause the regen not to work?

Thanks