Just a heads up guys:

Tests for diesel cars and lorries are to be tightened up to ensure vehicles have a critical exhaust filter if one had originally been fitted as standard, Roads Minister Robert Goodwill has announced.

Garages and testing stations will be required check for a diesel particulate filter (DPF) in the inspection of the exhaust system as part of the MOT test (or annual test for heavy vehicles) from February 2014.

The vehicle will automatically fail the MOT test if the filter had been fitted as standard but is found to be no longer present.

Excuse my ignorance, but why would someone remove the filter?. Cheers

absolutely no idea. Good Health

Maybe it slowed the engine down,, muffled?

Old news this. Basically all the new small diesels with low to zero road tax that all the Eco warriors buy have a filter in the exhaust system that if you don't do a decent high revs prolonged drive about once a month clogs up and causes all manners of hell, easy solution, chop it out, some garages may have done this and owners may be non the wiser as the 'running problem' will have been fixed, now you'll have to pay to have the system reinstated or fail. Europe screwing us again trying to force old vehicles off the road. Just buy a old diesel, no ecu, decat & straight through exhaust (one silencer box of minimal restriction purely for mot purposes) and run it on veg / veg mix / bio / or if your flush diesel lol.

And a right pain they are too . I do a lot of to-ing and fro-ing fairly short distances on low speed roads . Today I actually had to make a point of going via the motorway in a roundabout route to Chester on a fairly unecessary trip , just to satisfy the needs of the p.filter. Very green!

yeah people remove them as they get better MPG and better performance, plus don't have to have the worry of them blocking.
Its not just small cars that have them, according to theAA almost all diesels after 2009 required them to meet the tough exhaust EU requirements.

I kow many people have the box cut open and all the inners, removed then welded back up. I wonder if the MOT tester will be able to pick up on this type of mod. A welded box won't be that obvious once its covered in road crap.

It doesn't just affect "small diesels", larger cars also have them in.

If the car is properly maintained then a DPF shouldn't be a problem, the car will regenerate regardless of what road its been driven on.

The thing is these need replacing around the 80k mark and can cost anywhere from £100 to £500, depending on car and where you buy from.

And this is what people bitch about. If they read up on filters before buying their car, or just factored in the cost then it shouldn't make any difference.

On a Pug 307 a new filter and a top up of the additive can be done for £200. That will then last another 70,000 - 80,000 miles - that's a third of a penny per mile.

Quote Gibbo "If the car is properly maintained then a DPF shouldn't be a problem, the car will regenerate regardless of what road its been driven on.

I dont believe that its down to maintenance . This is what the AA have to say.

" Even if your driving isn't mainly urban/stop-start, changes to driving style may be required to keep these systems working properly.
If you're buying a new car and plan to use it mainly for town-based, stop/start driving it would be wise to avoid a diesel car fitted with a Diesel Particulate Filter (DPF) because of the possible hassle of incomplete 'DPF regeneration!"

AND p filters can cost £1000 + so Im not taking the risk!
Not too keen on getting it removed either , as it invalidates the insurance .

It all depends on the car, some Peugeots will regen happily on local roads and no high speed motoring is required, providing the additive tank is not left to go empty and the other components are maintained, such as glow plugs.

Some people and even mechanics think and say that glow plugs are never used and need never be replaced, which is why they're sometimes in hard to reach places in the engine bay. This is complete rubbish. Their entire reasoning is based on the fact the glow plug light doesn't come on unless its really cold.

They don't seem to know or understand or care about post-heating or the use of the plugs in a regen.

The trouble with the AA is they're pretty generic when it comes to vehicles.

Its certainly the case when they go out to a breakdown, stick on the code reader and just guess at what the fault might be based on the fault code.

They've misdiagnosed three of my customer's cars - told two that they needed two high pressure fuel pumps when they needed a fuel filter or a clean of the lift pump, and on another told him that his entire ABS system was faulty and needed a new ABS ECU when it was a faulty ABS sensor on one of the rear wheels.

As for DPF prices, have a look here:

http://www.cats2u.co.uk/

Much cheaper than the dealers, and no less quality as they sell OEM and type approved.

Hi Gibbo Thanks for that link, will put it to one side just in case.
Do all cars with the p.filters have a top up tank? The 2012 Skoda Octavia 2.00 TDI 139hp manual makes no mention of it and mechanic says 'heat and revs,nothing else' . Have we got one weve not been told about by any horrible chance?

A bit hard if like me, you don't know they exist in the first place.

They are a pain in arse. The one in my Passat recently started getting clogged and it would not clear automatically or by driving it at 2400 rpm till the light goes off as vw state. I ended up getting the garage to do a forced regeneration on it. This was despite the fact that the car makes reasonablely long motorway journeys most days of the week so theoretically it should not get blocked.

No, not all cars have them. Vauxhalls don't. Peugeot and Citroen definitely do. I've heard that the Focus does, but that wouldn't surprise me as they share the same engine.


There's some interesting info here:

http://c4owners.org/plugins/faq/faq.php?0.cat.10.44

And here:

Was this a one off or does it still happen? I can't speak for the VW but Pugs rely on several components working properly to do a regen - the glow plugs, glow plug relay, differential pressure sensor, additive tank level sensor, fuel cap sensor, cooling fan and cooling fan relays (phew!). If just one of those isn't working, it won't regen.

I was browsing the honestjohn forum the other day and someone mentioned that the DPF sensor is an issue on some VAG vehicles.

I think the problem of diesels is a combination of heavy sales patter and a lack of knowledge passed down from parents.

When I was a kid my dad told me that diesels were really only for distance driving, and they were dirty and smelly.

Things have changed, they're much easier to live with and run. My diesel purrs like a kitten and you can't even feel the engine when its stood at traffic lights.

But then they started to make small engines (I think you can get a 1.1 diesel now) and put them in small cars and tempted people with £30 or £20 or even £0 road tax and the great MPG figures.

I once had a Fiat Punto 1.3 diesel. Brilliant car, lots of power and cheap tax. It had one former owner, full service history and under 30,000 miles on the clock.

But after a while it started to play up. I took off the EGR valve and it was completely full of crud. It looked like it had done 90,000 miles (I've had a few old diesel Peugeot 306s with high mileage so I had experience in that field).

The former owner, a Wigan woman, used it to just pootle around town in, she never went on the motorway and Wigan isn't blessed with fast dual carriageways.

A good clean and a new MAF and all was well again. But that won't help people who have new cars with DPFs as standard or don't like to get their hands dirty.

And once the problems do start and the car is out of warranty, these are going to be someone else's problem in the second hand car market.

I've already seen a marked drop in value of 110bhp Peugeot 307s (with DPF) as opposed to the 90bhp (non DPF) models which are commanding a good price.

BBC Watchdog did a feature on it. Its not on iPlayer but if you Google "BBC Watchdog DPF" you'll find plenty of links relating to it.

I got my car, a Mazda 6, with a book value of £4500, for £1500 with a blocked DPF. With a new DPF supplied and fitted costing about £2000 the car was pretty much a write off. DPF Removal for £500 and it's as good as new. BMW DPF's also cost £1500 upwards.

If the exhaust is taken off and the filter removed from the top, and then rewelded then no-one will be any the wiser. ECU's also need reprogramming as the pressure sensors will throw up errors.

My brother has a company specialising in DPF's, He removes and cleans. This involves a DPF kiln and Suction.

It started getting blocked occasionally and the light would come on. About 10 mins up the motorway at around 2800 revs would clear it. It got to the point where it happened every day until it would not clear at all. After 2 days it went into limp mode. The garage did a forced regeneration to clear it plus the boost pressure sensor had failed too. I don't know if one fault caused the other but it cost the best part of a grand in the end. It has been fine since. This was about 6 months ago.

Who quoted £2000 though? I've seen them as low as £200 and as much as £450 on Cats2U for a Mazda 6.