Guys its been a while since i last posted but here goes.

Background - Most of my driving is done on fast A/B roads and motorway over 20,000 miles per year with the majority of journeys being in excess of 20miles. Have a 2.0ltr PD VRS with 78000miles on clock. Injectors were changed 2 weeks ago under recall. Had a look this morning and it would appear that i have the ''malaysian" DPF sensor. Regens were usually happening once a week with the DPF light very rarely coming on

Problem - Was parking on the drive on friday night and the DPF light came on. Didnt think too much off and thought that id clear it monday morning on my way into work. didnt drive the casr over the weekend so tried clearing it monday morning on the way into work - didnt clear. Tried again on the way back, took the car up to 75ish in 5th, went to change into 6th and suddenly a drop in power and the glow plug flashing. Pulled off motorway and turned the car off and then on thinking this may clear the glow plug light but now i have the DPF light, Glow Plug and EML.

Took the car down to a mechanic freind who scanned it (with a bosche scanner) and it read "diesel particulate fitler (Bank 1) faulty operation. So he looked into the DPF stats and it read 52% blocked and 38g of ash.

Couldnt do a forced regen without the car moving so suggested i try and clear it on the motorway and will attempt a forced regen tonight.

Since all the lights have come on the regen process has happened to my knowledge. Is this likely to be something other than a blocked DPF, maybe thinking a faulty sensor??

Any help gratefully appreciated

IIRC 52% blocked means the DPF has had it.

Sorry, my bad, just found this:

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

However this seems to suggest the DPF light shouldn't even be on at 52%?

Edited 25 July, 201213 yr by Anddenton

Hi,

there is a good chance that it is the G450 differential pressure sensor that needs to be replaced. There are a couple of recent threads above this worth reading to confirm. Not too expensive to resolve ~£55 for the sensor but will need to be adapted byVCDS or VAS after fitting.

The DPF is regenerable up to 95% by a forced regen before the DPF needs to be replaced.

See below for information from VW:

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

Sounds like it's a sensor issue:

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.

It is possible for the 'Made in Malaysia' sensors to fail too, although this usually brings up the 'exhasut gasses' warning light (amber outline of an engine) rather than the DPF light.

For what it's worth my PD170 regens much quicker after the DPF light has come on when in fourth rather than fifth.

75mph in fifth is just over 2,000rpm which isn't really enough, dropping it to fourth brings the RPM up to 3,000 to 3,500 which generates the required heat in the DPF much quicker to burn off the soot and complete the regen process.

You definately don't want to be in 6th, I was told motorway driving can cause the same issues as city driving as the low gearing/engine load together with the cold air passing over the DPF (exposed on the PD engines) won't allow for passive regen's - hence the DPF light comes on.

Guys,

Thanks all for the responses will see tonight if we can force the car into a Regen. I dont think the car will entertain a regen at the moment because the engine mamangement has put the car into limp mode. Ill see what happens and report.

drove back last night some 30 miles down the motorway in 4th gear at 2500 revs most the car wopuld let me do but nothing changed. would this tend to suggest a sensor issue?

The car won't attempt a regen when in limp-home mode (reduced engine power) - which you are in.

If the DPF is only 52% full then this alone shouldn't put the car into limp-home mode.

As you've successfully cleared the DPF light plenty of times before then I'm almost certain you have a dodgy sensor that is preventing the DPF from regenerating properly.

The problem is the more you drive the car the fuller the DPF will get of soot. This needs sorting before the DPF reaches 75-95%.

Be aware that to remove the DPF costs £450 so make sure you ask how much the sensor, forced regen and diagnostics will cost you as you may be better off getting it taken off.

The car is back to her normal self. Went out in it with a mechanic who had to do an authorised regen on it. EML went out giving power back, 5 mins later the glow plug went out and 15 mins later the DPF light went out.

DPF Soot content = 2.6% no increase in ash loading and the fault codes had also disappeared

Just be warned that a faulty sensor can be intermittent. i.e. the fault comes and goes.

You may well find yourself in the same situation in a few days/weeks/months time...

I may end up selling the beast soon anyway

Same problem I had.

Forced regen via VCDS new sendor fitted all sorted. Just a couple of regen's since. That was 6 months ago

I may end up selling the beast soon anyway

How come, not because of the DPF I hope!?