https://www.bbc.co.uk/blogs/legacy/x-ray/2011/11/diesel-dilemma.shtml "Diesel dilemma" (7 Nov 2011) BBC News] If the driver ignores the warning light and waits too long to operate the vehicle above 60 kmph , the DPF may not regenerate properly, and continued operation past that point may spoil the DPF completely so it must be replaced. [