P1448

DTC P1448

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P1448
- Diesel Particulate Filter Regeneration Frequency Too Low

Circuit/System Description

The particulates in the exhaust gases (solid particles in the exhaust exhibited as black smoke) are collected by the diesel particulate filter (DPF). When the filter becomes saturated with particulates, they are oxidized by incineration. We will refer to this incineration process as regeneration. When an active regeneration is commanded with the engine control module (ECM) a different engine calibration strategy is used to elevate the exhaust gas temperatures. The first event is to heat up the oxidation catalyst (DOC). Secondly the particulate filer temperature is elevated. These elevated exhaust gas temperatures incinerate the soot accumulated in the particulate filter.

The ECM will command a regeneration based on a calculated soot model. The soot model calculations are based on a number of different factors including:

* Distance since last DPF regeneration
* Fuel used since last DPF regeneration
* Engine run time since last DPF regeneration
* Differential pressure sensor values

The ECM monitors the DOC and DPF temperatures with inputs from two exhaust gas temperature (EGT) sensors 1 and 2, located before and after the exhaust particulate filter. The ECM also monitors the differential backpressure in the filter by a differential pressure sensor.

If the time between completed DPF regenerations become too infrequent, this diagnostic will fail.

Conditions for Running the DTC

* The engine is running.
* DTC P1448 runs continuously once the above conditions are met.

Conditions for Setting the DTC

* The engine control module (ECM) detects that the average running of time between the last two completed DPF regenerations is greater than 20 hours, not including idle time.
* The regeneration engine run time trigger is based on a 14 hour threshold. Therefore, the regeneration event was commanded but never completed, causing P1448 to set.

Action Taken When the DTC Sets

* DTC P1448 is a type A DTC.
* A message center or an indicator may display Clean Exhaust Filter.

Conditions for Clearing the DTC

DTC P1448 is a type A DTC.

Diagnostic Aids

* This DTC may set if the customer ignores the Clean Exhaust Filter message or indicator and continues to drive the vehicle under conditions that do not effectively clean and/or successfully complete two regeneration events.
* Cold ambient temperatures and short trip driving conditions may cause this DTC.
* Several incompleted regeneration attempts may cause this DTC.

Circuit/System Verification

Verify that DTCs P003A, P0047, P0048, P0101, P0201-P0208, P02A1, P02A5, P02A9, P02AD, P02B1, P02B5, P02B9, P02E0, P02E7-P02E9, P029D, P0300-P0308, P0402, P046C, P0420, P0545, P0546, P2032, P2033, P244B, P244C, P2463, or P2563 or not set.

If any other DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle. Diagnostic Trouble Code Descriptions

Circuit/System Testing

Important: Perform the Repair Verification after completing the Circuit/System Testing.

Verify the integrity of the entire exhaust system by visually inspecting for the following conditions:

* Damaged exhaust system components
* Loose or improperly installed exhaust system components
* Leaks, or improperly routed pressure lines-The smaller tube connects to the front of the DPF. The lines should have a continuous downward gradient, without sharp bends, or kinks from the differential pressure sensor to the exhaust particulate filter assembly.

Repair Instructions

Exhaust Particulate Filter Cleaning (LMM DPF Service Regeneration) Exhaust Particulate Filter Cleaning (LMM DPF Regeneration Enable) for Service Regeneration

Repair Verification

Notice: Refer to Diesel Particulate Filter (DPF) Service Regeneration Notice.

Certain engine control conditions can cause the EPF to overload with soot. It will be necessary to clean the EPF as instructed to remove the excess soot accumulation. To avoid the customer's return to the service department, perform the Exhaust Particulate Cleaning procedure.