What they don't tell you about Diesel Particulate Filters (DPF)!

If you own a diesel engine vehicle, you probably already place a lot of faith in your engine’s DPF. In essence, the job of the DPF is to remove carbon nanoparticles, or soot, from the exhaust gas of a diesel engine. The filter is supposed to auto-regenerate, burning away the accumulated soot so that the DPF can continue functioning without a hitch. So, in theory, apart from scheduled servicing, you’re not required to worry about filtering at all; the DPF does everything for you.

Unfortunately, diesel car owners know that this rosy situation is far from the truth. DPFs fail often, and it is very expensive to replace them. The thing is, even a replacement doesn’t solve your problem, because DPF failure is a symptom, not a root cause.

DPFs are so prone to failure because, despite being a good idea, they are basically added to fully functional engines instead of being built into them in an integrated manner. They rely on the property functioning of numerous parts and symptoms, which ultimately makes them so unreliable.

One primary requirement of consistent functioning of DPF that many users fail to meet is that in order for the regeneration to take place properly, the car must be driven at highway speed, 80 km/h, for a least an hour every fortnight. Travelling at city speed does not allow the soot to be burnt away from the filter. Most sellers, of course, conceal this fact to prevent frightening away potential customers.

But your DPF could fail even if you drive at the required speed. Other potential sources of problems include overfuelling due to a leak in the inlet air plumbing, induction leaks, leaky fuel injectors, use of wrong engine oil, leaky turbo oil seal, and several other major and minor factors that could wreck havoc on your DPF. So you see, a DPF failure is most often a symptom of something else that’s wrong with your car, and unless there is a proper diagnosis, you’ll be bleeding cash.

All these problems, on top of the ridiculously high price of DPFs, may make it sound very tempting to just do away with the damn thing. This is a bad idea. For one thing, you can’t simply pluck out the DPF, you’ll need a hellish lot of jailbreak coding for the engine to work without it, and that comes with its own set of problems and unreliability. Second, even if your engine malfunctions for other reasons, you will not be eligible for warranty or even succeed at a lawsuit if your DPF is deleted. Third, it’s quite illegal. You need your DPF to comply with the global emission standards. And fourth, the DPF actually serves a very important purpose: it removes carcinogens from the exhaust gas. So if you are at all concerned about cancer, as you should be, don’t even think of driving your diesel engine without a particulate filter.

So the takeaway from all this is to fulfill the speed requirement for regeneration, to get a proper diagnosis from a trusted technician if your DPF is acting up, and to correct the underlying problem before replacing your DPF. And if you are considering getting a diesel vehicle, it’s a good idea to educate yourself about what you are signing up for, because for sure your dealer isn’t about to tell you.