Another desperate owner with DPF issues

Engine, Exhaust, Drivetrain, ECU Issues and Fixes
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Paul
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Post by Paul »

Sorry for the lengthy “copy - paste” but I came across this, specific to VW group DPF and directly from a VW technical employee.

Completely clarifies what can and can’t be done, (corrects one of my previous posts on passive regen😊) and at the bottom, states what will and won’t be covered by warranty.........

(The reference to a “VAS tester” is when the car goes into the workshop,, is hooked up to the magic bix of tricks and a forced regeneration can be done)..........


VAG DISESEL PARTICULATE FILTERS

Courtesy of David Bodily Volkswagen Technical Support Specialist

Diesel Particulate Filter (DPF)

Detailed below is important information outlining the function and features of the Diesel Particulate filter which all members of your team need to be aware of.

Diesel particulate filters are becoming more commonplace on diesel engines, particularly sizes 2.0L upwards. This is in order to reduce the exhaust emissions as required by European legislation.

The prime reason for a DPF is to reduce particulate matter entering the atmosphere. Particulate matter is found in the form of soot, which is produced during diesel combustion. The DPF traps most of the soot which would normally travel down the
exhaust and into the atmosphere. The DPF can hold a certain amount of soot, but not a huge quantity and therefore it needs to go through a process called ‘regeneration’ in order to clear the soot loading. When the soot goes through a ‘regeneration’ process it will be converted to a much smaller amount of ash. The ash is non-removable. There are two types of ‘regeneration’, passive and active.

During long motorway journeys, passive regeneration will occur. This needs no intervention from the engine control unit. Due to the raised exhaust temperatures on a long journey (temperatures between 350 and 500°C), the procedure occurs slowly and continuously across the catalytic-coated (with platinum) DPF. The catalytic-coated DPF is situated close to the Engine, therefore the exhaust gas temperature is high enough (500°C) to ignite the soot particles. Due to this soot is burned-off and is converted into a smaller amount of ash.

Active ‘regeneration’ is when the ECU intervenes when the soot loading in the DPF is calculated to be 45%. The procedure lasts for about 5 – 10 minutes. Specific measures are taken by the ECU to raise the engine exhaust temperature to above 600°C, these include switching off the exhaust gas recirculation and increasing the fuel injection period to include a small injection after the main injection. The soot particles are oxidised at this temperature.

The ECU will trigger a regeneration process, if for some reason this is aborted, ie. customer slows down, stops etc, the process will be resumed when regeneration conditions are once again met, above 60km/h (38mph). This will continue for 15 minutes.

If after 2 attempts of 15 minutes, a successful regeneration has not been possible, the loading will increase. At 50% soot loading, the ECU will continue to maintain maximum exhaust temperatures of 600°C to 650°C to cause a regeneration process. The system will try to run a regeneration process for 15 minutes. If unsuccessful, the system will repeat this process for a further 15 minutes, if still unsuccessful, the DPF light on the driver display panel will then be lit.

The owners handbook states, the DPF symbol lights up to indicate that the diesel particulate filter has become obstructed with soot due to frequent short trips. When the warning lamp comes on, the driver should drive at a constant speed of at least 60 km/h for about 10 minutes. As a result of the increase in temperature the soot in the filter will be burned off. If the DPF symbol does not go out, the driver should contact an authorised Volkswagen repairer and have the fault rectified.

At 55% soot loading the DPF light is lit on driver display panel. At this point the customer should follow the advice in the handbook. If they ignore this information and continue driving the vehicle until the soot loading reaches 75% without successful regeneration, additional warning lamps will light up. At this point the customer will also be complaining of lack of power, etc.

At 75%, regeneration is still possible with the use of the VAS tester. Only when the loading is above 95%, is it necessary to replace the DPF unit.

Operating Status System Response
45% DPF Load Level 1
- Normal Regeneration
50% DPF Load Level 2
- Regeneration at maximum exhaust
temperatures
55% DPF Load DPF lamp
Regeneration from 60 km/h
onwards
("See operating manual")
75% DPF Load DPF, SYS and MI lamp
Torque limitation, EGR
deactivation,
Regeneration via VAG tester only
95% DPF Load Replace the DPF Unit

The Warranty department has confirmed that if there is no fault on the vehicle and DPF regeneration has been unsuccessful due to the customers driving style and the
customers failure to comply with the instructions in the handbook, DPF replacement will not be paid for by warranty.

Common causes for complaint

• Frequent short journeys – Regeneration conditions are not met. Not recommended for sale in the Channel Islands and inner city driving.


• Customers who continue to drive the vehicle with DPF light on – Continued driving with the DPF light on and without successful regeneration results in excessive soot loading of the DPF, to a point where it is above 95% loaded. At this point regeneration is not an option and replacement of the DPF is
necessary.

• Fault 18434 particle filter bank 1 malfunction – Common fault code. This does not only relate to the DPF itself, but the entire exhaust gas handling system. This can be caused by defective temperature sensors, pressure sensors, additive
system components (if applicable), poor connections, wiring issues, etc.

Important Information

• Before diagnosing a problem vehicle or attempting to perform an emergency regeneration, it is important to obtain a full diagnostic log and read out relevant measured value blocks. These MVB’s contain important information on the condition of the DPF system and are essential in diagnosing the fault. When the DPF light is illuminated, it does not necessarily mean that the DPF requires regeneration. For further advice, please contact Technical Support with the information from the diagnostic log and MVB data.

• If a problem vehicle arrives with the DPF light, the engine management light and the emissions light on. If during your diagnosis and reading of relevant MVB’s, you find that the soot loading exceeds 75% (but is still below 95%), an emergency regeneration procedure must be performed with the VAS tester. Further to this, the customer needs to be educated. They need to understand why the lights have appeared on the dash panel. Their attention needs to be brought to the owners handbook instructions, so that they are aware of what the DPF light means and what to do when it appears. This should prevent unnecessary repeat visits for regeneration purposes.
David Bodily

Volkswagen Technical Support Specialist
1st Sapphire SD
2nd Sapphire GTS
viewtopic.php?f=23&t=4296
Current 992 S Cab
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User avatar
Rab J
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Location: Ballymena

Post by Rab J »

GMAN75 wrote: Mon Jul 23, 2018 3:39 pm
stallturn wrote: Mon Jul 23, 2018 2:51 pm Has anybody noticed the potential big elephant sitting in the corner of this for-room?
If people are having problems with the diesel particulate filter, what might be the situation when the new emissions regulations arrive in September and petrol cars have a particulate filter?
Presumably they work in the same way?
Gasoline and diesel engines work entirely differently. For GPFs there won't, apparently, be a need to artificially increase the temperature in the exhaust to initiate regeneration. The regen should be entirely passive and work under decelerative conditions. Basically, this will all work on oxygen being forced through the system which, coupled with high temps in the exhaust already, will initiate the regen.
I do hope your optimism on the petrol particulate filter regen turns out correct, but the manufacturers talked in similarly glowing terms when DPFs were introduced. Sadly once real life motorists started to drive with them the problems that were never evident on hard driven test cars reared their ugly heads. I for one am glad that I got my petrol Porsche before I turned into a real-life guinea pig. No matter how much testing is done there's nearly always issues for early adopters.
Macan GTS Carmine with 21" black sports classics ---Gone
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Aixoise
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Joined: Mon Sep 24, 2018 11:50 am

Post by Aixoise »

My Macan was 3 years old in August 2018. It has been back to the dealers for this problem about 6 times. It even had to be towed to the dealership in Toulon after travelling from Manchester in 48 hours..1000 miles, all motorway.
And it has just gone into limp mode once again.
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Tim92gts
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Joined: Wed Dec 28, 2016 6:01 pm
Location: Essex

Post by Tim92gts »

If you get totally stuck there are now independents doing DPF cleaning, £165 + VAT at our local diesel specialist.
Tim
PP Turbo, LED PTV ACC Pano 20"Macans collected 6th September 2017
1992 928GTS
2003 996 Cab
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