How to speak DPF

| August 13, 2012

Isn’t cleaning what the regeneration process does? The regeneration process burns off accumulated soot, but it does not clean out the actual filter media that trap the particulates. And because the regeneration process will not burn off all the ash, eventually it will collect in the canister and fill it up. This normally happens around 400,000 miles for heavy-duty engines. But if you have a turbocharger or fuel injector failure, it could lead to the filter media becoming saturated before the mileage interval is met. So the little DPF light might indicate a bigger problem, depending on the mileage since the last cleaning.

Would that be an emergency situation? It’s not an immediate issue unless you’re around the 400,000-mile service interval. Usually you’ll know you’re getting close because the regenerations will be getting more frequent. If you notice more and more lights and regenerations well before 400,000 miles, you may have a bad injector or turbo. In any event, if you wait too long, your performance will fall off noticeably as the engine de-rates due to excessive exhaust back-pressure. So it pays to get the DPF looked at as soon as possible when regens are too frequent or the cleaning warnings are too early.

How long does cleaning take? There are two types of cleanings and both need to be done by a certified DPF technician. If you need to change out the DPF – usually because it is chipped, cracked, burned or melted – it takes about 2.5 hours, depending on vehicle or engine make. If your DPF is in good shape and just needs to be cleaned, you’re probably looking at four to five hours. Some manufacturers have quick exchange programs whereby you trade out your dirty DPF for a clean one.

How much does it cost? It’s not cheap. A DPF cleaning machine costs about $75,000, which helps explain why getting the unit cleaned can run you about $500. If you’re replacing the DPF, you’re probably looking at $1,200.

Can I just do it myself? You could, but it’s not recommended. The DPF element is made of fragile ceramic material, so you don’t even want to bump it. A noncore replacement DPF can cost as much as $4,500.

Editor’s note: Mack Trucks, Cummins, Detroit and Navistar contributed to this story. strives to maintain an open forum for reader opinions. Click here to read our comment policy.