Is it legal to drive a Vauxhall on the road without its DPF?

No. Road use of a Vauxhall with its filter removed breaks the Road Vehicles (Construction and Use) Regulations. From February 2014, a Vauxhall built with a DPF has automatically failed the MOT without one, and the penalty reaches £1,000 for a car and £2,500 for a light goods vehicle. For that reason we remove Vauxhall filters only from off-road and motorsport vehicles.

Why do so many Vauxhall Vectras used as taxis block their DPFs?

Because of the way they are driven. Most Vectra owners who come to us with a blocked filter use the car for local commuting or taxi work in built-up areas, much of it in and around London and the M25. The filter can only clean itself by regenerating, which needs the exhaust very hot for a sustained spell, and stop-start traffic and short hops rarely allow that. Each regeneration that fails leaves soot behind, and our Vectra 1.9 CDTi article follows the fault from there.

What are the signs of a blocked DPF on a Zafira 1.9 CDTi?

The glow plug or engine management light comes on, throttle response goes flat, and limp mode holds the revs below roughly 3,000 rpm. Fault code P1901 is among those listed in our Zafira 1.9 CDTi article. Fuel consumption worsens too, and in severe cases the engine turns hard to start, starts and then cuts out, or will not start at all, because it can no longer push its exhaust through the blocked filter.

Does a Vectra DPF fault also apply to the Zafira and Combo?

Largely, yes. The Vectra, Zafira and Combo share the same DPF system, so they share its weaknesses. The Combo runs a smaller 1.3 CDTi rather than the 1.9, though, so a fault still needs diagnosing on your own vehicle before the filter takes the blame. For a Vauxhall kept on the road, a professional clean with the underlying cause put right is the road-legal fix. Our DPF explainer sets out how the filter works, and you can send your Vauxhall’s details through our repair form.