Our big diesel’s DPF gets clogged
WHY WE’RE RUNNING IT
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Diesel ain’t that bad, right? That’s what we keep shouting, anyway, along with various industry bigwigs denouncing its demonisation. Well, the following episode has undermined my confidence somewhat.
Our fleet Vauxhall Insignia Sports Tourer was unable to regenerate its diesel particulate filter (DPF).
DPFS are designed to capture the black soot traditionally associated with diesel exhausts in order to help keep emissions down. The idea is they then clean themselves, or ‘regenerate’, during sustained periods of higher-rev driving by burning this soot out of the filter.
DPFS normally clog up, therefore, if you only do short, staccato runs. But I do loads of motorway driving. You’ll have seen my previous reports in which the Insignia has heaved camera kit, bicycles or my Lycra-clad mates along the M4 time and again.
You can imagine my dropped jaw, then, when the Vauxhall went into limp mode. Earlier, a warning message had sprung up on the dash: ‘Continue driving,’ it howled. So I did. Even though I really had somewhere I needed to be (I was hungry).
Ten minutes or so later a second message popped up. The filter had been unable to regenerate itself, the engine warning light glowed under my steering wheel and the car fell into limp mode.
At this point the handbook recommends taking the car to a dealership. So I rang and spoke to a variety of such franchises. Three weeks was the longest wait before the car could be seen, nine days was the shortest, which I duly booked.
“Am I all right to drive the car in the meantime, then?” I asked. “No.”
“Okay, do you have any courtesy cars?” The answer from all dealerships was that it would be at least two weeks until a courtesy car became available. But I live in the countryside and need to travel to work. Presumably it’s a warranty part, anyway? The response I received was thus: “Well, it’s not necessarily a warranty part. Vauxhall technicians will judge whether it’s under warranty based on your style of driving.”
They later decided that my 10,000 miles in six months was the style of driving that would warrant warranty treatment. But my astonishment here was twofold. Firstly, if my style of driving had been judged to be ‘incorrect’ – i.e. I only drove short distances – then I’d have to pay for it. And second, the Insignia’s 2.0-litre diesel engine is only managing to return 34.1mpg. I can’t imagine those who spend even more time on the motorway than I do would really want to give it a regular bootful for fear of cleaning out their wallet with a load of black soot.
The DPF on our car was discovered to be irreparable. The part had to be ordered from Germany, according to the dealership, so in total I was without a car for 16 days after just eight months of running it.
Honestly, the engine has felt like a 2.0-litre diesel-powered elephant in the room throughout my tenure. Emitting 186g/km of CO2 and with an NEDC combined figure of just 40.4mpg, it’s a really hard specification to justify.
There are plenty of other redeeming grounds on which to recommend the Sports Tourer – space, practicality, safety kit – but just be careful which box you tick in the powertrain section, especially given the political climate around it and the filter on the back.
Time to call Vauxhall – or a chimney sweep