GM Service Manual Online
For 1990-2009 cars only

Exhaust Particulate Filter Cleaning LF8 DPF Service Regeneration

Caution: Tailpipe outlet exhaust temperature will be greater than 300°C (572°F) during service regeneration. To help prevent personal injury or property damage from fire or burns, perform the following:

  1. Do not connect any shop exhaust removal hoses to the vehicle's tailpipe.
  2. Park the vehicle outdoors and keep people, other vehicles, and combustible material away during service regeneration.
  3. Do not leave the vehicle unattended.

Caution: To avoid extremely elevated exhaust temperatures, inspect and remove any debris or mud build up at the exhaust cooler located at the tailpipe.

Notice:  Due to the elevated engine temperatures created while performing this procedure it is imperative to keep the front of vehicle in an open environment, with the hood open, away from any walls or buildings. This will ensure proper airflow across the radiator.

Conditions for Running

The following conditions must be met in order to enable DPF Service Regeneration:

       Important: Do not refuel the vehicle during DPF Service Regeneration.

    • There are no active DTCs displayed.
    • The battery voltage is greater than 10 volts.
    • The engine speed is idle speed. Idle control volume position is MIN.
    • The exhaust gas temperature (EGT) sensor 2 are less than 130°C (266°F).
    • The engine coolant temperature (ECT) sensor 1 is between 70-115°C (158-239°F).
    • The brake pedal and accelerator pedal are in the released position.
    • The transmission is in Park or Neutral.
    • The parking brake switch is ON.

Test Procedure

  1. Clear all DTCs with a scan tool before proceeding with DPF Service Regeneration.
  2. Observe the scan tool DPF Regenerations Completed parameter and record the value.
  3. Inspect the following fluid levels before and after this procedure:
  4. • Engine oil
    • Engine coolant
    • Power steering
    • Transmission
    • Fuel level should be over 15 percent to ensure a successful regeneration.
  5. Park the vehicle outside the facility, away from any obstacles, place the transmission in Park and apply the parking brake.
  6. The DPF Service Regeneration will be terminated if any of the following actions are performed:
  7. • The ignition switch is OFF.
    • The parking brake switch is OFF.
    • Press, operate, the DPF switch.
    • Applying the accelerator pedal
    • Selecting Drive or Reverse
    • Commanding DPF Service Regeneration OFF using the scan tool or disconnecting the scan tool from the vehicle
  8. Turn ON the ignition for 30 seconds. DO NOT start the engine. This is to relearn exhaust differential pressure.
  9. Turn OFF the ignition for one minute.
  10. Put the gearshift lever in the N position, and pull the parking brake lever firmly.
  11. Install a scan tool.
  12. Clear the DPF data with a scan tool.
  13. Start the engine.
  14. If the idling control knob is used to increase the engine speed, return it all the way to the left to reduce the engine speed.
  15. In the case of a vehicle fitted with a PTO unit, stop operation of the PTO. Return the PTO switch and the external acceleration control to their initial positions.
  16. Perform the DPF Normal Regeneration with a scan tool.
  17. Press the DPF switch. The DPF indicator lamp, which is green, comes on, and the engine speed automatically increases the regeneration starts. Stay near the vehicle during regeneration.
  18. Perform the regeneration is completed. the regeneration is normally completed in about 20 minutes. When the DPF indicator light goes OFF, the regeneration is complete.
  19. Observe the EGT 2 parameter with a scan tool. Ensure the temperature is less than 130°C (266°F).
  20. If more than 130°C (266°F), let increase 1,000 RPM without load.
  21. Accelerate the engine to wide open throttle (WOT), accelerator pedal full travel, and read the Exhaust Differential Pressure parameter when the EGT 2 parameter is reached to 150°C (302°F).
  22. If the Exhaust Differential Pressure parameter is less than below the specified value, ash cleaning must be performed.

Service Regeneration Unsuccessful

    • The scan tool DPF Regen Inhibit Reason parameter, will display a reason for not enabling DPF Service Regeneration. Refer to the parameters that are displayed.
    • The scan tool DPF Regeneration Status parameter will display Active or Required depending on the current commanded state of regeneration.
    • The scan tool DPF Regenerations Completed parameter did not increment.
    • The scan tool DPF pressure will display less than below the specified value. If the Exhaust Differential Pressure parameter is greater than below the specified value, replace the exhaust particulate filter.
    • Observe the EGT 2 parameter with a scan tool. Ensure the temperature is less than 130°C (266°F).
       ⇒If more than 130°C (266°F), let increase to 1,000 RPM without load.
    • Accelerate the engine to WOT, accelerator pedal full travel, and read the Exhaust Differential Pressure parameter when the EGT 2 parameter is reached to 150°C (302°F).
    • Observe the DPF Pressure parameter with a scan tool.

Service Regeneration Status Fault Table

DPF Regeneration Parameters

Successful Regeneration

Unsuccessful Regeneration

DPF Regeneration Status

Complete

Active or Required

DPF Regeneration Reason

None

Fuel Used

Engine Run Time

Distance Traveled

DPF Pressure

DPF Regeneration Inhibit Reason

None

Varies