Workshop Repair and Service Manuals GMC SIERRA

Diesel Particulate Filter


The vehicle has a Diesel Particulate Filter (DPF) as part of the exhaust system toreduce vehicle emissions. The DPF requires a unique exhaust tailpipe with an exhaustcooler. The exhaust cooler mixes air with the exhaust to lower the temperature beforeit leaves the tailpipe.

The DPF, the tailpipe, or other exhaust system components must not be altered. Inspectregularly and clean any mud or dirt from the exhaust cooler, especially where theexhaust cooler connects to the tailpipe and the openings where fresh air enters thecooler. See “Exhaust System Inspection” underMaintenance Schedule.

The DPF will clean itself as part of normal operation. Several factors including fuelconsumed, hours of engine operation and miles driven are monitored by the Engine ControlModule (ECM). The self-cleaning occurs approximately once per tank of fuel.

Notice:Permanent damage can occur to the DPF or related componentsif the required Ultra Low Sulfur Diesel (15 ppm sulfur maximum) orlow ash CJ-4 engine oil is not used. This damage wouldnot be covered by the vehicle warranty.

Under certain driving conditions, such as stop-and-go traffic, the filter cannot cleanitself. The CLEANING EXHAUST FILTER KEEP DRIVING UNTIL MESSAGE IS CLEARED messagecomes on when the DPF is dirty and needs to perform a self cleaning.

For the filter to clean itself, the vehicle must be driven above 50-km/h (30-mph)until the CLEANING EXHAUST FILTER KEEP DRIVING UNTIL MESSAGE IS CLEARED message goesoff. This will take about 30-minutes.

Warning:During DPF self cleaning or during extended idling inP-(Park), the exhaust system and exhaust gases are veryhot. Things that burn could touch hot exhaust parts under thevehicle and ignite. You or others could be burned. Do not park, oridle for an extended period of time, near or over papers, leaves,dry grass, or other things that can burn. Keep the exhaust areaclear of material that could ignite or burn. SeeParking over Things That Burnfor moreinformation.

Notice:Extended idle should be avoided because the DPF system is notcapable of self cleaning at idle. During extended idle operation,monitor the instrument panel telltale lights and Driver InformationCenter for messages and take appropriate indicated action.Continued idling with the warning light/message on could causeirreversible damage to the DPF requiring repair and possiblereplacement that might not be covered by the vehiclewarranty.

You will also notice a change in the exhaust sound and engine idle speed. This isnormal. SeeVehicle Messages.

If you continue to drive with the DPF warning message on and the exhaust filter isnot cleaned as required, the malfunction indicator lamp and the ENGINE POWER IS REDUCEDmessage will come on and dealer service is necessary. SeeMalfunction Indicator LampandEngine Power Messages.

Vehicles with DPF have specific fuel and engine oil requirements. SeeWhat Fuel to Use in The U.S.orWhat Fuel to Use in Canada and MexicoandEngine Oilfor more information on those requirements.

Extended idling in P-(Park) can cause exhaust parts and gases to become very hot.Keep the exhaust area clear of material that could ignite or burn. SeeParking over Things That Burn.

For vehicles with Power Take-Off (PTO), monitor the instrument panel cluster for lightsrelated to the DPF.

SeeAccessories and Modificationsfor important information if you are considering adding accessories or modifyingthe vehicle.

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