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Is this DPF Regen?

I've noticed something odd about my fuel economy.

Each day on my commute I make a trip of around 21 miles each way to/from work comprising some local roads, but mostly motorway. The trip is very consistent in duration, speed, traffic, etc. I monitor the fuel consumption each time I do the trip (by having the trip show on the centre display behind the steering wheel).

Most days this is around 55-60 mpg, varying a little based on how much traffic I encounter. Every now and then (perhaps once per month) it drops to about 35-40 mpg, for no reason that I can determine. No traffic jam, no change in driving behaviour, nothing obvious. That's a significant change, you would expect that I would notice something different.

Anyone else had this? Seems very odd. Always returns to the standard performance after this odd trip.

I've got an A200D. Overall, very happy with fuel consumption.
 

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Even though I don't have the diesel I have had dpf diesels in the past that have the same characteristics when adding extra fuel for dpf regen. Wouldn't worry about it as it means it's doing its job.
 

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Hi first post. I have had my Aclass 220d AMG from new about 4 weeks. Regularly getting 65 mpg on long trips, urban about 55mpg and thats even on a very short run so very happy with that.
Today on doing a run of 20 miles which I have been done before and got about 55mpg for the trip, it suddenly dropped to 23.5mpg for the trip. I have always used Eco mode and I also noticed today on the economy display in the cockpit that I used to get 999mpg showing with the foot of the accelerator now that now only shows 85 max aprox, I cant remember exactly but definitely not over a 100mpg. So strange its my first Merc and wondered if I have accidentally triggered something. Thanks for any ideas you may have.
 

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How many miles have you done?

Sounds like it might have been the DPF regeneration process, same thing happens on mine, first time was at around 500 miles? May also have noticed a strange smell and the fan staying on afterwards?

If so then it will be fine next time you get in - but will happen again when it needs to be done again though :)
 

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Hi Thanks for the response. Now thats interesting, done just over a 1000, I have also noticed a smell, it was like a burning smell.
So the DPF could also effect the dramatic drop in mpg, will be doing a short run tomorrow and see if it has disappeared. During the 20 mile run today at the very end of it with foot of the accelerator it did for a second go to 999mpg, then quickly reverted back to 85mpg. Had the burning smell about 4 times since new when getting out of car, but did not notice the mpg dramatic drop.Thanks so much for enlightening me and I will report back tomorrow after my journey.
 

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Yeah is definitely a burning smell for me too when it happens, along with a drop in mpg for that journey (don’t notice it as much on a slightly longer journey as it won’t run for the entire time).

fingers crossed all good for you now 😀
 

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Update, went on a short trip today and the problem still exists but not so bad up to 35 mpg when usually 55mpg for same trip and coasting up to 400mpg instead of 999mpg. I did ring my Mercedes garage up and have booked it in for Friday just in case it does not rectify itself. I mentioned DPF, they said could be but quite a dramatic drop 50%. I personally think it may clear itself if I do a long run. My first 3 weeks out of the 4 weeks I have had it, no probs at all getting 55-60 mpg combined. Interesting that Reteb has same problem, I was wondering how often that happens ? Thanks again for all the replies.
 

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I don’t use my car during the week but every few weeks I experience a similar issue, maybe every 1,000 miles? I think it’s just how the re-gen works and I believe it’s dependent upon the type of driving you are doing at the time as to whether it squirts a bit of fuel into the exhaust or not.
I don’t think it’s anything to worry about. My overall mpg is still pretty good and getting better
 

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My previous car was a Diesel Leon and if I stopped the car during l a regen it would smell extremely hot and the fan would keep running.It would do a regen regularly although I am not certain if it was time based or reacting to sensors around the DPF, my drive to work was only 15 mins each way. I was told that when it requires a regen temperatures circa 400 degrees are required in order to burn off the particles in the filter. This would normally take place on a long run. But if you have done short journeys and not generated sufficient temperature then the car some how uses extra fuel to generate the heat required to perform the regen. I never noticed if my fuel consumption changed during this process. I hope this makes some sense as I don't know all the techy details.
 

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I have a MB 2019 V167 GLE 300d (OM-654) and I use bluedriver OBDII reader to monitor DPF regen info.
Below are what I have:
1. Normally, my car will do DPF regen around every 3X0KM (Normalized Trigger for DPF regen up to 100%)
(Pic 1 show 310KM and start doing regen, one day and 80KM later, pic 2 show 356KM)

2. When my car totally finish the regen, my car will not have any burn smell.

3. During the regen process and shutdown my car, my car will have burn smell.
And when car is in idle but not in P mode, the dynamic fuel consumption is 3.0 ~ 3.5L/Hour
But after system success finish DPF regen, the dynamic fuel consumption is drop back to 1.0 ~ 1.5L/Hour

4. Normally when I found my car is doing DPF regen, I will switch to S mode and driving.
If engin can keep in 2K RPM, normally my car can finish the DPF regen in 10-20 minutes.
And my car will not have burn smell any more.
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My previous car was a Diesel Leon and if I stopped the car during l a regen it would smell extremely hot and the fan would keep running.It would do a regen regularly although I am not certain if it was time based or reacting to sensors around the DPF, my drive to work was only 15 mins each way. I was told that when it requires a regen temperatures circa 400 degrees are required in order to burn off the particles in the filter. This would normally take place on a long run. But if you have done short journeys and not generated sufficient temperature then the car some how uses extra fuel to generate the heat required to perform the regen. I never noticed if my fuel consumption changed during this process. I hope this makes some sense as I don't know all the techy details.
 

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Thanks for all great feedback I did not know there was a separate thread on the matter so my post was merged. Interesting that it lasts for about 50 miles. I am not quite up to that yet so hopefully it should rectify itself soon.
 

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Hi everyone.
I have an early 2021 a220d, and am wondering what triggers the regen process, and how often the car should do it.
My car seems to regen often, it's only gone a week since the last one, then did it again today. In fairness I've done about 700 miles in that week which is about double my normal.
What's everyone else experiencing?
Thanks,
Craig.
 
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