Author Topic: Mazda 6 2014 2.2 Diesel Carbon build up  (Read 12282 times)

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Offline mrkarlos

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Mazda 6 2014 2.2 Diesel Carbon build up
« on: June 14, 2020, 09:02:45 pm »

Hi all,
I’m looking for some help and advice please.
I have a 2014 2.2 diesel which has just over 79k on it. I purchased it from new, having it serviced by Mazda with all the recommended recalls and updates.

So the other day I had the dpf inspection required light come on? So got it booked in to Mazda to get this checked out.

Took a call from the garage to be told that they have tried to a force re generation on it but it cannot be performed ?
From what I’m being told the injectors are faulty, Numerous sensors need changing and that the head  needs de-coking due to carbon build up oh and the dpf is probably blocked. Also forgot to mention the oil level rising. Has anybody else had issues with there car after the engine software update ( AJ024* ) and the Intake shutter valve ( AK016A ) recalls?  Not to sure if any these recalls could have contributed to the failure of these parts as the garage has said that one part failed then in turn has taken out parts there after.

I did read on Honest John forum that somebody had the shutter valve update and the garage performed a Carbon clean which I don’t think was done to mine?

Clutching at straws I no but just wondering if anybody else has had similar problems and what the out come was as from what I’m being told the cost of the repairs is going to outway the value of the car so I might as well scrap it, certainly not what I expect from a 5 1\2 year car.

Thanks in advance

Offline DaveMc89

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Re: Mazda 6 2014 2.2 Diesel Carbon build up
« Reply #1 on: July 14, 2020, 05:53:26 pm »
Did you get anywhere with this? My last 6 had issues with the rising oil levels and pressure problems that turned out to be the £10 injector seals following two lots of the dealer cleaning the sumo pickup and changing the oil pressure sensor.

Offline Medianjungle

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Re: Mazda 6 2014 2.2 Diesel Carbon build up
« Reply #2 on: December 29, 2020, 01:10:42 pm »
Just had a similar issue. I have a 67 plate with just over 26000 miles on the clock. Engine management light came on and Mazda are saying that the engine needs a decoke. Can’t believe and engine with such low mileage needs one. ????

Offline Elwood

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Re: Mazda 6 2014 2.2 Diesel Carbon build up
« Reply #3 on: December 29, 2020, 08:01:19 pm »
Probaby it's because of the extraordinarily low mileage that the engine needs a de-coke. The car has averaged only 2000 miles per year which equates to approx. 32 miles per week over a year. Used like this, the engine has never had chance to really warm up and burn off all the pollutants which cause carbon build-up. Seems like it might have been used as a shopping car for very short runs only. Engines need using to keep them at their best. I wouldn't think the engines of cars which spend a lot of their lives driving on motorways would ever need a de-coke.

Offline apav

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Re: Mazda 6 2014 2.2 Diesel Carbon build up
« Reply #4 on: December 30, 2020, 06:45:30 am »
26,000 miles over 3 years is about 8,000 miles per year which is the UK average.

You can drive once per week and do that mileage, or drive every day. If you drive every day, it is still 20 miles per day, which even in stop start traffic is enough to warm the car. The stop start system does not operate when the engine is cold.

The problem with the carbon build up is more of a design feature of these engines. For sure they were not designed to be driven in stop start conditions but this is how the roads are nowadays.

The expression driving on the motorway is a bit misleading nowadays. The motorways have the highest speed limit in the UK but try commuting to work and you will find out that you spend a lot of the time parked with the handbreak on.

Then you try again on the weekends and it is marginally better. Most people use the cars for commuting to work and driving away on the holidays. On both scenarios they use the motorways only to be parked idling to keep them warm or cool.

Motorway driving used to mean higher speeds which required higher revolutions. This had the potential to take away the accummulated dirt. But as nowadays the motorway traffic is slow moving, the expression should be replaced with something like drive the car long enough without the need to stop.

The speed and the revolutions do not matter as long as you can keep the car moving at the highest gear. Then you have a chance to burn out the accummulated dirt.

But the problem here is that the natural burning cycle of these engine result in excessive carbon. If you only use the car for commuting, shopping and holidays, then you cannot avoid this dirt accummulation.

Luckily, most drivers do not have this problem because they buy the car in finance and swap it with another every couple of years. For the unlucky drivers that they do not do that, the decoke is a good option to cover for the bad design.

The other option is to drive away on the weekends and get some fresh air but most people do not do that. If people were giving a chance to the car to drive some considerate time without stopping, then it could clean up a bit but the problem would return with the standing traffic reality.

When the current generation of E Class was introduced, the reviews mentioned that the engine sits at 1,100 rpm at 70mph thanks to its 9 speed gearbox. So in the traditional thinking that driving the car on the motorway will clean up the engine, this will not happen because of the low revolutions but because of the time the engine will keep running non stop.

Mazda never got it right with the diesel engines but there is no way they will admit that.

Offline Siw

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Re: Mazda 6 2014 2.2 Diesel Carbon build up
« Reply #5 on: December 31, 2020, 03:49:46 pm »
My Mazda had similar issues to yours, rising oil level and occasional EM light with the fault code saying the dpf was blocked.
I got a code reader/deleted and deleted the codes and took the car for a spirited drive once a month, keeping the revs above 2k in 3rd/4th for over half an hour.
Problem never came back.
It’s worth noting that unless you clear the fault code your engine will not perform a regen no matter how you drive it.

Offline apav

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Re: Mazda 6 2014 2.2 Diesel Carbon build up
« Reply #6 on: January 01, 2021, 07:41:50 am »
What code reader did you buy Siw?

Offline Siw

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Re: Mazda 6 2014 2.2 Diesel Carbon build up
« Reply #7 on: January 02, 2021, 11:17:26 am »

Offline apav

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Re: Mazda 6 2014 2.2 Diesel Carbon build up
« Reply #8 on: January 03, 2021, 07:22:23 am »
That looks good and it also comes with updates which means that as long as the hardware is good, it will keep going.

The big question is whether removing the battery really clears all the DTCs like you could do with the reader.

Offline Siw

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Re: Mazda 6 2014 2.2 Diesel Carbon build up
« Reply #9 on: January 03, 2021, 11:51:06 am »
That looks good and it also comes with updates which means that as long as the hardware is good, it will keep going.

The big question is whether removing the battery really clears all the DTCs like you could do with the reader.

Depends how the codes are stored. Either way I prefer to use a code reader as you know it’s deleted it and it also tells you what the fault is. Plus you can use it on multiple vehicles.

Offline apav

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Re: Mazda 6 2014 2.2 Diesel Carbon build up
« Reply #10 on: January 04, 2021, 06:16:38 am »
Yes that is true. It says on the online service manual for the first generation 6 that if you disconnect the battery, all the DTCs will be deleted, but then you do not know what the problem was.

Did you try the Forscan option before buying the code reader?

https://forscan.org/home.html

https://forscan.org/forum/viewtopic.php?f=5&t=836

It seems that once you have a bluetooth devide, starting with the forscan may be the cheapest option.

Offline Siw

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Re: Mazda 6 2014 2.2 Diesel Carbon build up
« Reply #11 on: January 06, 2021, 07:06:29 pm »
Yes that is true. It says on the online service manual for the first generation 6 that if you disconnect the battery, all the DTCs will be deleted, but then you do not know what the problem was.

Did you try the Forscan option before buying the code reader?

https://forscan.org/home.html

https://forscan.org/forum/viewtopic.php?f=5&t=836

It seems that once you have a bluetooth devide, starting with the forscan may be the cheapest option.
I just got one knowing that it’d come in handy on both the car of the van.
I used to have a full opcom setup on my laptop for my old Vauxhall, that did everything including adding/removing ecus.

Offline mareng73

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Re: Mazda 6 2014 2.2 Diesel Carbon build up
« Reply #12 on: October 30, 2021, 11:03:37 am »
Mkarios.
Mine is  a 2014  and had from new.  Back in 2018/9  after those two updates which in actual fact caused the EGR to operate more to keep combustion temperatures down and thus NOx low, this caused coking of the inlet system. Mazda carried out inlet decokes from the EGR through the throttle valve  to the  inlet valves free of charge. This happened following a service visit as opposed to a VOSA recall.
If you haven't had the decoke  then enquire  at the dealers.

Another reason for rapidly increasing oil level  is frequent regens.
Using Forscan what is your regen frequency mileage. Recommended is 150- 200 miles between regens. If you are down to double figures under 50 miles then you have serius problems looming.
What sort  of  monthly mpg do you get.
Your car is in the right age group for th problems mine experienced. It doesn't happen to all  of  that year, but usually starts to appear in the 40-50 k mileage range first by P243C code appearing.  The dealer goes through all the troubleshooting and changes the DP  DPF sensor thats at the left rear of the engine on the top, easily seen. Small black box with two hoses out the  bottom  and an electrical connection. They clear the  code   but it comes back. Changing this sensor will set you back £200+,  yet its only a few minutes job.
A few months/ 1000 mile  later same code. Car is running fine though. So the dealer replaces the sensor again but on warranty. Same thing happens.
The sensor is ok, but the troubleshooting they use doesn't  go far enough.

A savvy SM will smell a rat that something is not right.  As regen frequency increases the ECU picks this up and throws the above code.
The problem is faulty injectors, worn nozzle holes to be exact and the cure is new injectors and they will set you back some serious pocket money, even with a dealer and Mazda goodwill payment.
I know, it happened to me. From 30  miles or less  between regens and low 40's mpg even touring, the figures changed to 200 miles between regens and up to 61 mpg touring and 55 in the town. With the 20p increase in diesel  even my pence per mile dropped quite a bit.
This problem started after year two as evidenced by my average  mpg becoming worse  each  year.

How long the new ( not exchange  refurbished)  injectors last we shall see. On the pressure opened injectors hey would last the lif of the car , perhaps 200/250k, but common rail with  the far higher opening pressures it could be less.

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