: Ensuring the life of your diesel emissions system

07-22-10, 11:06 AM
Seems these days cars are begining to be ever more complicated. Unfortunately the government are not helping. The introduction of a diesel particle filter on the majority of diesel cars in 2006 was hailed by the government as a great way to cut C02 emissions. The idea was to have a capture chanber with a "carbon cake" to absorb soot from the engine exhaust gas. Once this "cake" was sufficiantly full then the engine would inject extra diesel to heat up the filter to 800 degrees c and burn the soot off. Apparently this is cleaner than just expelling it in the first place. Problem is that if you dont drive at least constantly for 15 mins per week the DPF doesnt have chance to heat, therefore with the extra help is still not hot enough to regenerate. Soot builds up and up and eventually the DPF becomes blocked. Manual regens can be done at cadillac dealerships using tech 2 but this will cost you. So how can you ensure your filter is free flowing? Well follow the points below:

1. Always go on a long run once a week. I would suggest 30 mins rather than 15. It takes 15 mins for the cycle to complete.

2. On your long run keep the car at 2500-3000 rpm, this may mean driving in 4th or 5th. This will allow for optimum temp.

3. At junctions on any trip pull away hard once in 2nd gear or 3rd. If you look in the wing mirror you will see either a plume of black or trail of black soot. This stops the soot accumulating in vast quantities on the DPF cake.

4. If the regen process has started, dont stop the car, continue driving even if this means doubling back on yourself before getting to your destination. This will ensure the process completes and no stray unburnt diesel ends up in your sump.

All in all the DPF is a major pain to the diesel driver and is counter productive as you have to drive the car at high revs and for long trips just to stop the filter clogging. This not only increases fuel consumption but also emissions. For some DPF horror stories affescting all manufacturers google DPF problems. Or look at this unluck guys post:


07-22-10, 01:59 PM
i remember when mine went in for it's 1st service with me that it needs a software update for the getting rid of waste from the exhaust.
it wasnt a recall it was just a service notifaction.
wonder if it had anthing to do this.

07-26-10, 05:19 PM
I've had my 'new' 2009 (built 2008!) 1.9 TDI for almost 5 months now and after 5500 miles, things seem to be ok. Interesting reading about the DPF, my daily journey to work takes exactly 35 minutes each way of mostly dual carriageway or motorway driving, so I guess I don't suffer some of the problems that some get with short journeys to work or to the shops. Almost every journey I do in my Caddy, is what I would consider 'a good run'. I haven't seen a single plume of smoke from mine. I will be changing the oil at 10000 miles (I estimate reaching this by November). All in all, I'm extremely chuffed with the car.

07-27-10, 05:03 PM
My 2010(built2008)has now covered 4500 miles in approx 5 months without any problems.My journeys are of varying lengths and I am averaging about 40mpg(180hp auto estate).I am not aware of any DPF action and will await the DIC(Driver Information Centre) to advise me if anything is untoward.Great car and I,m even using the sport button!If I was redesigning this car the only change I would make is to the suspension,keep the softness but avoid the "wallowing".

07-27-10, 05:09 PM
The BLS should have been a great seller as it's a great car

07-27-10, 05:15 PM
I agree 100% but the original price was far too high to penetrate any market.I think the new Saab 9.5 will fail due to the pricing point.Hope I am wrong though.S70RMP--would you make any changes?

07-28-10, 08:24 AM
My BLS is a 2006 1.9 TD. I Bought it in Feb 10 with 33k on the clock, its now done 44k. I only wrote the original post here to warn people of the potential pitfalls with the modern diesel car. I for one have had all sorts of problems with mine. Unfortuanalty my DPF had a faulty sensor (hidden to me at purchase) which stopped the DPF regenerating correctly. After having the new sensor fitted and the software update from Cadillac it has literally taken me 6000 miles of driving in the ways detailed above to clear the DPF (engine management light finally went off last week, I flatly refused to pay 1000+ from cadillac for a new filter). If I could change anything about the car it would be the removal of the DPF, removal of the EGR valve (it will clog up with soot, mark my words, I have already had to replace mine), paint it properly (my lacquer pealed off the rear bumper, and underside passenger side skirt simply shead its paint, down to plastic), build it properly by people other then GM (wing mirror soft close packed up on passenger side, dual mass flywheel is on it way out). All will/have been fixed under 3rd party warranty but thats not the point. I feel there are a lot of people on the forum that have just bought pre reg cars with low or no miles on them and are happy at this time. There is only S70RMP who has an early version like me and I think they have been lucky with not many faults (touch wood). I hope your cars perform well and are reliable but to me I am stuck with mine for at least another 15 months an I only hope nothing else goes wrong with it as I do 24000+ miles per year.

07-28-10, 04:43 PM
i'd have made sat nav and Xenon's standard from day 1

and better automatic box !