Recognising a DPF regen

[Deepjoy22]

Hi all.  Like many I guess, I’ve done far less miles in the last nine months than normal.  And I’ve also done a lot more short journeys (with a diesel).  The result of this is that the oil level reached the X mark after just 6000 miles – so an extra oil change. 

From previous postings, I can understand this is caused by a large number of interrupted DPF regens.  My question, is there any way to be able to know for sure if a regen is in progress.  I’ve noted comments relating to fuel consumption and some have noted a smell.  In an ideal world I wish there was a dashboard light, but in the absence of that is there any other identifiable way, such as monitoring the engine icon on the fuel economy / i-Stop screen

Thanks.

[rmvf]

Hey Deepjoy,

Ive only had the one diesel so i might be wrong but from memory i think the instantaneous fuel comsumption reading is poorer during regen. The smell is unreal, i cant understand how at travelling at 70mph the smell can ingress into cabin but it certainly did on my mazda 6.

[rmvf]

Found this below

I filled up with fuel and joined a motorway for my daily commute home, then reset my average mpg.  It's the same route I use every day and would normally expect about 50mpg displayed, but I suppose I was chasing it on a bit, and it was windy, so let's say a displayed 44mpg (40 actual) would be expected.  However it almost immediately started a dpf regen, noticeable by the instant mpg dropping from about 50 to about 18.  My commute home is 22 miles, and takes about half an hour, with motorway for the first two thirds and fast A-roads the final third.  The regen lasted til nearly the motorway exit.  On arriving home my average mpg showed 22mpg.  So, according to the computer -my car uses a full half gallon to do a regen.

[Bert321]

is there any way to be able to know for sure if a regen is in progress.  I’ve noted comments relating to fuel consumption and some have noted a smell.

The post 2015 facelift model with the MZD stereo has 3 icons with halos around them on one of the screens.  The engine one shouldn't have a halo while the engine is cold etc, but after that it should... except when it's doing a regen.  The fuel consumption also drops like a stone, and there's a roughness to the engine, most noticeable during overrun when, for example, slowing down for a motorway exit.  You might also notice a white puff of smoke on acceleration, and might notice a smell if you switch the car off while it's doing a regen.  The three 2.2 diesels I've owned over the last 5 years or so have done a regen every 180 miles or so, and they last maybe 8 miles at motorway speeds.

The pre 2015 facelift has the same tell tales except it doesn't have the icons on the stereo.

[Deepjoy22]

Thanks for the pointer re the engine icon; I can watch for that in conjunction with miles covered.

Last question; what other things could cause the engine icon not be have the halo once the engine is up to operating temperature.

[Bert321]

what other things could cause the engine icon not be have the halo once the engine is up to operating temperature.

I can't answer with certainty since I don't always watch that screen, but any time I look at it the halo is on unless it's doing a regen or the engine is cold.  Maybe it would be off if there was a fault, or it was in limp mode etc?

[Notoriousdhb]

Thanks for the pointer re the engine icon; I can watch for that in conjunction with miles covered.

Last question; what other things could cause the engine icon not be have the halo once the engine is up to operating temperature.

Hi, I don't know why the engine light would not glow other than when cold or conducting a regen. However, i experience this and usually during the colder months. As I monitor my regens, I can rule the regen being the reason. When it does happen and usually at lights, I just touch the accelerator and the it usually glows - it just rules out "is it regening" Hope this is of some help to you.

[Notoriousdhb]

Thanks for the pointer re the engine icon; I can watch for that in conjunction with miles covered.

Last question; what other things could cause the engine icon not be have the halo once the engine is up to operating temperature.

Another thing I have noticed is that regens are only successful when conducted at say 50mph+ in constant flowing traffic. I find, if I'm caught out in start-stop driving then my oil levels rise by about 1mm.