Frequently Asked Questions

The most direct way is to enter the OEM part number in the search field on the Skyline website to find the correct replacement Skyline DOC or DPF. Or, you can try searching by engine model or by browsing the collection. Contact a Skyline dealer if you need assistance.

Skyline has no minimum order rules, but your local distributor might. Contact us to find the distributor in your area.

No. Skyline DPFs and DOCs are sold, installed, and supported through a network of specialized distributors across North America. Contact us to find the distributor in your area.

If you are interested in becoming a Skyline distributor, contact Skyline for more information.

No, but its associated division ESW Group does. Visit the ESW Group website for more information about CARB-verified retrofit systems and parts.

Skyline DPFs and DOCs are backed by a 3 year, unlimited mileage warranty. Consult Skyline's terms and conditions for details.

Contact a Skyline distributor or consult your owner’s manual. If you still have questions that have not been answered, email us here.

No registration is necessary. Your proof of purchase – the receipt from the Skyline distributor -- is your warranty card. The start date for the warranty period is the date of purchase.

Fuel and oil contain inorganic additives to help protect your engine and extend the life of the oil. During the combustion process, they are turned into ash, which collects in the DPF over time. Unlike the black carbon in the exhaust, which is removed during the regeneration process, the ash can only be removed by a cleaning device. This requires the DPF to be removed from the engine. The cleaning interval varies for each engine manufacturer (and sometimes between engines from the same manufacturer) and can be found in your vehicle’s service guidelines. You should follow the engine manufacturer’s recommended cleaning intervals for your Skyline DPF just like you would for the original DPF.

Note that the amount of ash is directly related to the amount of oil an engine consumes. High oil consumption or high hours of service means more ash in the DPF and may require more frequent cleaning.

The Skyline DPF is designed to be an exact replacement to the OEM part, so you maintain the Skyline DPF just like you maintain the OEM DPF. Refer to the OEM service documents for instructions and cautions.

A network of DPF cleaning services has developed since DPFs became standard equipment on trucks and buses. Some Skyline distributors also have cleaning services, so your Skyline distributor would be a good starting point to find a reliable cleaning service.

If a filter cleaning machine is approved by the OEM, it can be used to clean your Skyline DPF.

No, unless DOC maintenance is specifically called out in your engine’s maintenance instructions.

In recent years, some OEMs have started to use a different type of DPF material in their heavy-duty aftertreatment systems. Since Skyline matches the OEM design, our DPFs use the same type of filter material.

These DPFs are made from a material called Silicon Carbide (sometimes abbreviated as SiC, its chemical formula). It differs from the more common material (cordierite) in color and how the filter is assembled. Silicon carbide is dark gray and the DPF is almost always a collection of smaller pieces that are cemented together, often in a checkerboard pattern. In contrast, a cordierite DPF is typically tan and built as a single continuous cylinder. The photos below illustrate these differences.

Unless the OEM specifies otherwise in their service documents, a cordierite filter must always be replaced by a cordierite filter, and a silicon carbide filter replaced by a silicon carbide filter. Although both DPF types provide nearly 100% PM reduction efficiency, the OEM’s regeneration strategy and fault codes are designed around a particular material, so switching material without OEM authorization could cause undesirable effects.

A poorly maintained engine lowers your fuel economy, increases emissions, and shortens the life of your engine and emissions critical components such as the DPF and DOC. Deferred or neglected maintenance items may include the following: restricted air filters, stuck EGR valves, faulty fuel injectors, faulty turbochargers, and degraded charge air coolers.

Regular vehicle, engine and after-treatment maintenance (including the DPF), will yield more vehicle “up time,” with reduced operating costs, and maximize your return on the investment that you made in the vehicle.

As an engine runs, the DPF collects solid particles called particulate matter (“PM”) which consists of carbon, unburned fuel and oil, the ash from fuel and oil additives, as well as any other contaminants from the exhaust. Over time, the DPF will fill with PM. The process of removing the combustible part of the PM (the carbon, unburned fuel, and unburned oil) is generally called “regeneration.”

Under driving conditions with the engine producing high exhaust temperatures – on a highway or pulling a heavy load – the catalytic coatings on the DPF and DOC are sufficient to keep the DPF clean. This cleaning process that takes place without any activity by the engine is called “passive regeneration.”

When the exhaust temperature is not sufficiently high, the vehicle’s exhaust system relies on auxiliary fuel injection to raise the temperature of the DPF to a level at which the most of the PM is oxidized. This process is actively controlled by the engine‘s controller and therefore called “active regeneration.” The active regeneration occurs periodically and is not noticeable to the driver. Numerous sensors on the engine and exhaust system provide input to the engine‘s controller so it can trigger and control the process.

Most engines have another type of active regeneration that is initiated by the operator when the vehicle is standing still. This process is called "stationary regeneration" or "forced regeneration." During the process, the engine controller modifies the engine speed, intake air flow, EGR rate, and other functions to allow the DPF temperature to reach a suitable temperature. Consult your engine or vehicle owner's manual for details.

In most cases your vehicle relies on both passive and active regeneration to keep the DPF clean and the vehicle operating normally.

Extended periods of idling shorten the lifetime of your engine, consume fuel unnecessarily and load up the DPF . In addition, some states, private entities (like warehouses or loading docks), and many municipalities have strict anti-idling laws or policies.