Home Forums Chat Forum Merc Viano enigine warning light DPF regen?

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  • Merc Viano enigine warning light DPF regen?
  • ads678
    Full Member

    So the engine warning light came on while I was driving down to the Alps a week or so ago. 14 plate Merc Viano. I drove approx 1500 miles with it on and it was limiting revs only when pulling away or going up a big hill. Was driving well at 70 odd MPH generally though.

    Just dropped it off in the garage and they have said it needs a DPF regen and pressure something or other….

    Thought that was a bit wierd as I was driving long distance at pretty high speeds so thought it would have cleaned out, but I don’t really know anything about this sort of thing. Can anyone shed any light as to why this has happened or what it means for the future? It generally only gets driven on motorway type journeys, try to avoid too much local driving as its a big filthy diesel and drinks fuel on short journeys.

    TheFlyingOx
    Full Member

    Dunno about the Mercs but I read the Transporter has a sensor that measures actual soot vs expected soot in the DPF, or something like that, and if the difference is too big it needs a forced regen at a VW garage. Think the regen needs 20 minutes sustained at 2000rpm+ for the VW. If you’ve somehow managed to not get a standard regen, either through stop/start city driving or not quite managing to hit the magic rpm for the magic number of minutes, then I guess you could have something similar to the VW error.

    ads678
    Full Member

    Yeah it was a pressure sensor and regen they said. Maybe the sensor is knackered so it isn’t regening when it should. Hopefully the new sensor will mean it works as it should in future…🤞

    maccruiskeen
    Full Member

    what sort of milage have you done?

    Are they saying the sensor itself is faulty? or that the sensor is reporting a fault?

    The particulates the DPF filters are mostly soot and little bit of ash. Soot is flammable and it burnt off during a regen, but ash isnt flammable so over time the ash will accumulate, so theres a point where the filter mostly contains ash and a regen won’t shift it. Thats when a sensor would be correctly be reporting an increase in pressure, rather than be at fault.  A lot of garages don’t seem to take that into account and try to correct the function of the DPF when the reality is the filter is just full and needs replacing.

    An awful lot relies of your garage knows their arse from their elbow rather than looking at fault codes. DPF problems can be the DPF itself and related systems – but they they can also be the result of all sorts of things up-stream from the DPF – turbo problems, leaking injectors, the wrong oil… resulting in too much crud finding its way into the filter- not detecting and dealing with these means work on the DPF is just a temporary fix and in a few months you’ll be paying for that DPF work to be done again AND fixing the real problem (if you’re lucky enough that you only go through that cycle once)

    flannol
    Free Member

    There are ways the garage can sufficiently clear some of the crap out the DPF aren’t there?

    maccruiskeen
    Full Member

    There are ways the garage can sufficiently clear some of the crap out the DPF aren’t there?

    using words like ‘ultrasonic’ 🙂

    Theres a lot of snake oil

    benpinnick
    Full Member

    If it’s like my nissan then you get either a dpf light or a warning light due to pressure. The problem is if you get the engine warning light then dpf cycle is disabled….

    As above though every now and again it needs a proper clean out it would seem. Be aware forced regens can ruin your engine oil so if they don’t do it expect to change it sooner rather than later. Simple test is to look on the dipstick and see if there’s too much ‘oil’ (because it’s also now full of diesel).

    ads678
    Full Member

    Cheers all. It seems ok now but I suppose I’ll have to wait and see.

    I couldn’t get it into the normal garage I use, which is a Merc specialist, Indy 2 man garage. They were booked up until June. The one I went to is another German auto specialist, bigger but well regarded still, so hopefully they’ve done a proper job…..

    I’ll check the oil though.

    timba
    Free Member

    Under EU legislation “pollution control devices” must be subject to manufacturers’ testing and good for 160,000km. In the real world various bodies suggest a minimum of 80,000 miles, assuming that you do all the right things and use correct oil. Correct fuel shouldn’t be a problem because that’s been regulated at the pump since 2000.

    You can break a DPF but it’s more likely to be either driving style or associated sensors that cause problems. You can clean a DPF out, but how effective it is I don’t know… Ceramex is one such https://www.ceramex.com/

    There’s a mobile mechanic on YouTube that has plenty of DPF problem-solving videos, O’Rileys Autos, I think

    molgrips
    Free Member

    Thought that was a bit wierd as I was driving long distance at pretty high speeds so thought it would have cleaned out

    It should yes, but as above some things cause the engine to smoke, and when you have a DPF you never see the smoke, it just blocks your DPF quickly. And if you regen it without fixing the other issue it will block again.

    snotrag
    Full Member

    DPF differential pressure sensor pressure before, pressure after) is a common and easy fix, cross ref the part numbers and a buy a Bosch part (the Merc part without the Merc stamp). On most. Merc diesel engines and configs it’s clipped up near the back of the valve cover on two short hoses from the dpf. Two new hose clips to fit. Half an hour. Take it for a long drive. Sorted. Easy.

    ads678
    Full Member

    It’s done nearly 120k miles. I’ve had it since 87k. Mostly used for trips away with minimal local driving. Gets 2 trips to the alps/Pyrenees each year.

    Hopefully it’s sorted for a while now. I’m starting to do a few bits and pieces myself but some stuff I just don’t have the space/knowledge/patience so I’ll have to pay and trust garages. The one I usually use is really good, but he’s very busy!

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