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171 Mazda 6 DPF issue 'Soot accumulation in DPF is too high'

  • 12-01-2022 9:32am
    Registered Users Posts: 419 ✭✭ rockdrummer4

    Hi guys,

    Bought a 171 Mazda 6 (platinum auto model) last sept 2020. 63,000 km diesel.. Since sept I have done abt 6000 km, mostly motorway driving..

    'Soot accumulation in DPF is too high' came up in Nov 2020, didnt go into limp mode... went back to garage and they did a manual regen. But same error came up again at beginning of Jan 2022, went back to garage and they ran a regen again, but they are also gonna clean the DPF. will this do the trick?

    AFAIK, they obviously hooked up computer to run manual regen and no other error came up, i.e. no problem with some sensor etc...

    Any help would be appreciated.. most expensive car I have bought and dont want issues :)

    Cheers, C



  • How much and what kind of driving are you doing? You say "mostly motorway driving" and 6000km, but how long are the trips? And how often? And just to clarify, you got the first DPF error in November 2020, and then the next one was 14 months later (this month). The 6000km is since September 2020, not 2021. So less than 6000km in a year - which would be regarded as very low mileage for a diesel. A 171 that had 63,000km when you bought it in 2020 was averaging over 15,000km a year under the previous owner(s).

    Multiple short trips without a long one to trigger a regen will cause the DPF to clog up.

    That said, I had a previous car that was constantly getting a blocked DPF, despite me doing 50km round trips every day, and a 300km round trip every Sunday. Multiple garages (including one who traded on the notion of being dedicated DPF specialists) took a look at it, and none could figure out the problem.

  • Balls yeah, fecking confused with years :( Sorry

    Bought Sept 2021.. error in Nov 2021 and jan 2022!! 6000km in 4 months.. motorway driving mainly balbriggan to Clonee - just over 40km each way, with Trips to Wexford, Carlingford etc...

  • Ah, ok, well that changes things alright. You look like you're doing enough mileage and the type of driving to keep a DPF clear.

    Only thing I'd say is don't assume that the garage ran proper diagnostics on it. They might just have forced the regen without looking at the underlying issue. A quick scan for fault codes is not a proper diagnostic. I don't know about cleaning the DPF. I had it done in my old car, and it helped for about a month. That's not to say that it wouldn't work in another scenario. There's two residues in a DPF. There's the soot, which is the particles that are getting filtered out of the exhaust fumes. They eventually build up and require the regeneration process to burn them off. Then there's ash. The ash is the residue from the regeneration burning the soot. Over a longer period of time, the ash accumulation becomes a problem. And there's nothing the car can do to remove the ash. I think it's ash that DPF cleaning claims to remove. But I think modern cars are supposed to be smart enough to differentiate between soot and ash accumulation, and your error message is a soot one.

    When I brought mine to a DPF specialist, they handed me about 200 pages of diagnostic logs, taken over a number of days (both driving and in the garage). They weren't able to pinpoint the reason that the car was refusing to regenerate. Previously, the DPF pressure sensor and sensor pipes had already been changed. EGR valve had been checked. A boost pipe leak had been identified and fixed. DPF had been removed and cleaned. This was over the course of a year of investigation. The car was over 10 years old and over 250,000 km on it. A new DPF was one option, and probably required since the DPF was probably damaged from being blocked, but the consensus was that there was something else happening that was causing the underlying issue. Because of all this, I ended up scrapping the car. But that was at the end of a fairly exhaustive (excuse the pun) process. You're not anywhere near there yet.

    If I were you, first step would be to make sure that a full diagnostic and log is done to see exactly what is going on with the engine. Not just checking for error codes - looking at the various values of the engine's performance to make sure that they're all as they should be.

    Oh, one other thing. Make sure the car is serviced properly with the correct oil. The oil is a very important part of the regeneration process, and an incorrect oil for the engine will hinder it. Be sure you're getting the exact spec oil the manufacturer requires for the specific engine.

  • Thanks Gregor for the comprehensive reply, great info.

    Yeah, time is my enemy here.. as the car is still under warranty until middle of march 2022. Have asked for extension for DPF, but im worried that if they clean DPF it will take longer for soot to accumulate and then warranty will expire and Im on my own..

    Im not sure to what extent the garage will go to troubleshoot this, they will probably just try clean and say see how ya go, then the above worry applies...

    May take it to Mazda garage before warranty is up, them check it and if issues take it back..

  • Just checking the oil as this could be an indication of failed regens etc

    Please see pics, to me (dont know much about cars), the oil level seems ok?, but the oil itself looks a bit black, not an oily colour? Have just owned petrol cars in the past so dont know if oil is different for diesel cars?

    What ya think?

    Thank you

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  • Oil in a diesel will be black, that's normal.

    Not your ornery onager

  • Get dpf mapped out be best thing to do

  • It is bad advice! Sure, it was bad idea to buy wrong car too. Diesel is designed for driving. Obviously that car did not got enough driving and now there is massive problem. Still it is possible to save if there is not too many times forced regenerations. DPF can survive only very limited numbers of forced regenerations. Why people force the regeneration is time saving. You better drive, drive, drive and it regenerate naturally.

    The next is not bold statement (sorry). Almost 1 and half year and only 6k, obviously the diesel is not for you. If you do not drive long distances (minimum once a week over 1 hour trip), buy electrical! Then you can drive even 1 meter and stop so many times as you want. You do not like the answer, not my problem.

    Car keys programming, add key, all keys lost, key blade duplicating, original key repair

  • Isn't the Mazda diesel engine a total nightmare anyway, apart from minor issues like a DPF problem?

    Not your ornery onager

  • But mazda are well known for dpf problems causing oil to be diluted by diesel went fail to do regeneration and then the destroying the engine. Personally if I made mistake of buying a mazda diesel and first signs of dpf problems I be getting it mapped out or selling it ASAP

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  • I agree, sell ASAP. 1.5 years and 6k, it is hard to suggest any car over 1 liter. Even electric car battery can die if not enough usage. 6k, rented car or taxi may be good option. Sorry, but I do not see any other reasonable solution.

    Car keys programming, add key, all keys lost, key blade duplicating, original key repair

  • Yup, mate had one as company car and just over 2 years in it was done. Disgraceful really.

  • If I remember rightly, there have been several post on here before, concerning Mazda diesel engines and DPF and engine oil issues. Their petrol engines on the other hand, seem to be pretty trouble free. Not too many good options all things considered, it is unfortunate that you did not do a bit of research before purchasing. Nowadays, there are many makes with DPF technology, and they all have the possibility to give DPF trouble, but Mazda DPF's seems to give problems over and beyond the norm, which are incredibly difficult to fix. Personally, if I could, I'd be getting rid of it.

  • The engine oil issues, afaik, are caused by unburnt diesel contaminating the engine oil which basically wrecks the engine eventually.

    Not your ornery onager

  • If you read through the thread the OP corrected himself, the car was purchased 2021 not 2020 so 6k in 4 months

  • Thank you yeah, got messed up with me years :) So basically over 6000km in 4 months..

    I did do research.. and it got great reviews. Plus I have 2 neighbors with Mazda 6's and they swear by them ! Ive had Mazda' in the past, albeit MX5's, so petrol and they were great.. In my opinion Mazda have a relatively good reliability reputation. Not like BMW or Audi, which are not so reliable and when go wrong can cost a fortune to fix (I could be wrong with this, or could be alot to do with luck!!). I was going to get BMW 330e, but with the driving I do the electric motor would not have been good, and loadsa issues with that one..

    In fairness if you search 'a model of any car and problems' you will get loads of issues with any car. People will only open threads like this if they have problems, no one will ever open a thread like this saying they have no problems :)

    Since getting the warning light I have done alot of digging into this, I can find very little information on 171 Mazda 6's DPF issues, or years around 171. All the forums and youtube vids relate to earlier years i.e. 2008 - 2012...

    In any case garage taking car under warranty next week, hopefully get it sorted (fingers crossed)..

  • My 2011 Mazda had a similar problem, turns out the sensor was borked in the exhaust that was picking up the soot. Back then i had the DPF innards removed and remapped, but its a bad idea now with changes to the NCT looming.

  • Yeah, OK. those posts must have been the ones I was thinking about so. I remember when I was looking to change the car about 3 years ago, there was an absolutely lovely Mazda diesel for sale, and two of the brothers in law, who would be very savvy about cars, ( plus I would have a fair bit of experience too, having worked as a mechanic for a good Nr of years )owned two petrol engined Mazdas, and could not fault them. But I passed on the Mazda that time anyway based on these reviews. You are right about car look at a particular car, all you will get is the problematic ones, but of course, that's the whole point of forums. I hope that you get your problem sorted, and make it clear to them that if the problem re occurs, you will be coming back, out of warranty or not. And make sure that you keep a record of all that has occurred since you got the car, just in case you have to take it further. ( you probably are doing this anyway.) A friend of mine bought a brand new VW Tiguan a few years ago, and everything went well for a while then the dreaded DPF problems started to appear. So back he went to the main dealer, who duly rectified the problem, and off he went, Until the problem reappeared, and so the DPF dance started. When he complained about this happening, he was told that their driving style was the cause of all the problems,,,,his Wife was an agent, travelling around the town's etc, multiple stop's and start's. (And to be truthful, that was the cause) Anyway, eventually the dealership refused to do any more when the warranty expired. But he refused to accept that and took them to court. They won their case, and got a full refund.

  • Excellent, thats good to know :) Thanks jmreire.. will have to persist with garage.. get a record of what they do next week. Dont have record from them about the 2 regens they have done in Nov 21 and Jan 22, but I have noted it down... Hope they dont read this, and it doesnt come to this anyway :)

  • Just a thought in passing, while in theory a trip from Balbriggan to Clonee should be enough for a regeneration, if you're doing that trip at peak periods with significant traffic to contend with, it may not be enough time at a high enough engine rev and temperature to allow a regeneration to complete, and over time, that may have added to the problems.

    The Mazda engine is not high revving, so if you end up being stuck in slower traffic for part of the journey, which at peak periods is very likely, you will struggle to complete a regeneration. My son has been driving Mazda 6's for the last 4 or more years, and would have had another if they'd been able to deliver, but he's had to move to a different vehicle now, and doesn't like it as much, but he was able to do long runs on a regular basis (Clare to Dublin), so never had regeneration issues, but I'm well aware of other people who have had significant issues with the same engine where they've been doing a lot of local driving, without a good blow out on a regular basis.

    It won't help your economy, but you might end up having to do some of your trips in lower gears and therefore higher engine revs, depending on what the result of the dealership investigation turns up.

    Shore, if it was easy, everybody would be doin it.😁

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  • Yeah I kinda tought about this, how would ya know if car was doing a regeneration? If noticed it was, could just keep going, and let it finish.. Anyway last time Id buy a diesel.. :)

    Motorway's are pretty OK in the morning these days, and coming home about 1:30pm each day, so not really starting and stopping on either journey. In saying that I dont belt it in, usually a steady 100 - 110 kph, revs seem to be about 1800 at that speed.

    Between middle of Sept (when I bought car) and start Nov when warning light came on, I did a fair bit of driving in and out to Clonee everyday (not so much now as work from home 3ish days a week due to covid), trip to wexford, Ardee, Dundalk etc.. Should have had plenty of opportunities to complete a regen(s)?

    The first time the warning appeared, I did go for a spin in low gear to get the revs up, and was also going into work in 5th gear to see if that would clear it, but no joy :(

  • The first time the warning appeared, I did go for a spin in low gear to get the revs up, and was also going into work in 5th gear to see if that would clear it, but no joy :(

    5th gear? Typo?

    Not your ornery onager

  • See what the dealership comes up with, it is possible that there is an issue there that's not been flagged as such by the computers, but the result is preventing it regenerating. I don't know if there's a specific indication that a regeneration is in progress on the M6, there's no indication by default on the Citroen I have, but apparently there is a way to have an LED that lights up when it's doing a regen, but I've never put one in, as I've not seen any significant issues with mine.

    I will watch with interest to see where this goes, I suspect that there will be quite a few people following to see what happens.

    Shore, if it was easy, everybody would be doin it.😁

  • Its a 6 speed Mazda, so lower a gear to get the revs a bit higher. Its an automatic if that makes a diff to DPF, but ya can go semi and manually change gears..

  • Yeah I'll post back how it goes, cheers... But probably wont know for months. ATM no warning light as they did a regen on the 6th.. And hopefully garage will give me a record of what they do next week.. but it will be a while (hopefully not) b4 the warning comes up again! Not nice with a big enough loan on a car that Im unsure if its gonnaa f**k up in the near future..

  • What ever the gear you are in, you would need the revs to up to the 2'500 + mark to have a regen. Its been a pet peeve of mine that while we have seriously hi teck computerized systems in cars, with warning lights for everything, they will not put a discreet light / icon on the dash showing when a regen is taking place. In Mercedes its possible to "jury Rig" a warning light to show when its happening, so I'm pretty sure that it can be done in other makes as well. It would certainly help regens,,,,,if a warning light / icon came on while you were driving, then you would continue until the regen was complete before switching off the engine. As it is, many regens don't complete before the engine is switched off, leading to all kinds of complications and problems later on with DPF's getting clogged up.

  • Totally agree... would the temp gauge go up a little? I noticed that after the last manual regen the temp was up a little and after driving for a while the temp went back down to normal? Very annoying, as you say if its in the middle of a regen I wouldnt stop, no way of knowing tho...

  • Yes maybe a little in some cars, but for sure the temp in the DPF can rise so hot, it can be felt while standing outside the car near where the DPF is located. Can be as high as 550 c. and some people can actually get a "burning" smell. In one episode of the Sopranos, the son takes his girlfriend out for a spin, and parks in the woods on ground covered in dry leaves. They are settling in to a hot romantic session, when smoke is seen coming up from the ground, and they have to do an emergency evacuation while the car goes up in flames. I'm strongly thinking of installing a regen warning light in my own car, even though it has never given me any regen problems. However, my previous car had a problem with regening,,,,it tended to show as an increase in the engine oil level. To achieve the high temps needed for a regen, extra fuel is injected into the cylinders. Multiple failed regens leave an excess of unburnt fuel in the cylinders, which find its way down into the sump, and mixes with the engine oil...which is not good.

  • The 2 most expensive things in your life - House and car...

    Pyrite on the house (getting this done via pyriteboard), Mazda DPF (hopefully via warranty).

    Alot going on so...

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  • For sure, you have enough and more than enough on your plate!!!! I hope that 2022 will see a big change in your life fir the better!! Good Luck.