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Ask Jake Cheek Your Own Question
Jake Cheek
Jake Cheek,
Category: Chevy
Satisfied Customers: 24
Experience:  Automotive Technician at Hendrick Chevrolet
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My 2015 2500 6.6 went into low power mode and i dont

Customer Question

my 2015 2500 6.6 went into low power mode and i dont understand why...
JA: Are you fixing your 2500 yourself? What have you tried so far?
Customer: i took it in to the dealer about a week ago because it wouldn't stop regening. they told me that i needed to let it finish its cycles. apparently because of my driving the truck never really finished its regen cycles.
JA: Anything else you want the mechanic to know before I connect you?
Customer: no
Submitted: 4 months ago.
Category: Chevy
Expert:  Jake Cheek replied 4 months ago.

Hi my name is ***** ***** to JustAnswer. They are right you should complete the Regeneration. It will go into limp mode if it is not done after a certain amount of time.

Over time, the soot trapped on the cell walls acts to restrict exhaust flow through the DPF reducing its effectiveness as well as reducing engine efficiency. This restriction in exhaust flow produces a pressure drop across the DPF that increases as the once porous cell walls become saturated with trapped soot. A DPS monitors the pressure drop across the DPF and provides the ECM with a voltage signal proportional to soot buildup. Once soot buildup reaches a specified limit, as signaled by the increased pressure drop across the DPF, the ECM commands a regeneration event to burn-off the collected soot during normal vehicle operation. Regeneration events occurring during vehicle operation are known as normal regenerations as they occur automatically and without driver knowledge. In general, the vehicle will need to be operating continuously at speeds above 48 km/h (30 mph) for approximately 20–30 minutes for a full and effective regeneration to complete.

The frequency of normal DPF regeneration is a function of the engine run time, miles driven, and fuel consumed since the last regeneration event. To initiate a regeneration event, the ECM commands the HCI to inject additional fuel upstream of the DOC in order to create the additional exhaust heat necessary to promote regeneration and burn-off the collected soot.

During regeneration exhaust temperatures may exceed 550°C (1,022°F) due to the rapid catalytic combustion of soot within the DPF. Conversely, under low engine speed or light loads, exhaust temperatures may be too low to promote proper regeneration. To protect the DPF catalyst from thermal damage due to excessive soot combustion or from sulfate poisoning at low temperatures, the ECM monitors EGT sensors upstream and downstream of the DPF during regeneration. If the vehicle is slowed to idle speed during a normal DPF regeneration, the engine may maintain an elevated idle of 800 RPM until the DPF is cooled to a calibrated temperature.

Should the EGT sensors indicate that regeneration temperatures have exceeded a calibrated threshold, regeneration will be temporally suspended until the sensors return to a normal temperature. If regeneration temperatures fall below a calibrated threshold, regeneration is terminated and a corresponding DTC is set in the ECM.

Under most conditions, the soot collected within the DPF burns off during normal regeneration cycles. Periodic regeneration prevents the buildup of soot from reaching a level where its burn-off could produce damaging high temperatures within the DPF. Vehicles operated at prolonged low speed or low loads where normal regeneration does not occur will eventually reach a high soot load condition. When the increased pressure drop across the DPF is detected by the DPS, the ECM illuminates the DPF lamp in the instrument cluster and sends a Clean Exhaust Filter message to the driver information center (DIC). The owner manual diesel supplement describes how the vehicle should be driven in order to enable normal regeneration.

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