Sootable case for treatment?

In April 2009 I bought a one-year-old Nissan X-trail. At the end of July, having covered 2000 miles in France in just over a week the particulate light again came on together with the Malfunction light. After some initial reluctance and a prod from Honest John my local dealer did agree to rectify the problem under warranty although I was continually reminded that my driving style was the cause (slow and short journeys). It took four days - so can't have been all that simple. This week the Particulate light again came on and I decided to avoid all misunderstanding to drive it on a 12-mile section of the M40 at the legal maximum speed and whilst doing this the Malfunction light again came on. I have now taken this up with Nissan direct because local dealers just say that I must be driving it slowly and on short journeys. Nissan themselves say that that is the problem and I must pay for any work and parts unless the dealer happens to find that my driving style is not at fault. I am very suspicious over this. I would have no difficulty in getting many signatures to support me over my driving style

Asked on 24 April 2010 by J.H., via e-mail

Answered by Honest John
Yes, you are driving it on too many short runs from cold and at engine
revs too low for the DPF to regenerate. It is not vehicle speed that regenerates the DPF, it is engine speed. So to regenerate it you need engine speed of at least 2,500rpm for at least 10 miles. That may mean running in 5th or even 4th gear to stay within the speed limit. Does seem to be a problem with the Renault engine in the current X-Trail, the 2.0 diesel engine in Mazda 6s and the 1.3 Multijet diesel in FIAT 500s and Vauxhall Combos.
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