Skip to content
Tahoe / Yukon Service Manual

DTC P226D

Engine Controls and Fuel - 3.0L LM2 Diesel | Diagnostic Information and Procedures | Document ID: 5507735 Diagnostic Instructions Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach. Diagnostic Procedure Instructions provides an overview of each diagnostic category. DTC Descriptor DTC P226D Particulate Filter Deteriorated Substrate Circuit/System Description The diesel exhaust aftertreatment system includes an under hood catalyst converter which consists of the main diesel oxidation catalyst and the coated Diesel Particulate Filter (DPF). The purpose of the DPF is to collect particulates from the engine exhaust in order to minimize discharge of soot to the atmosphere. The soot particles accumulate in the channels of the DPF and are burned off at regular intervals through a process called regeneration. This prevents the DPF from clogging. The ECM commands the DPF regeneration after calculating various vehicle conditions such as DPF pressure difference, exhaust gas temperature, engine oil quality, engine speed, etc. Excessive accumulation of the soot in the DPF can cause a drop in the engine performance. During regeneration, additional fuel is injected via multiple post injections in order to increase the exhaust gas temperature. During this period, the DPF temperature is raised to approximately 600°C (1,112°F) and the accumulated soot is oxidized or burned off into carbon dioxide (CO2). Conditions for Running the DTC DTCs related to the following system/component = Not Set – B9 Ambient Air Temperature Sensor – B75C Multifunction Intake Air Sensor – B131 Exhaust Temperature Sensor – B154 Diesel Particulate Filter Exhaust Differential Pressure Sensor Calculated Particulate Filter Soot Accumulation is between 1 and 400% Engine Speed is greater than 500 RPM. The ignition is ON or the engine is cranking or running. The ignition voltage is greater than 11 V. The ambient temperature is warmer than −12°C (10.4°F). The particulate matter sensor is operating. The DTC runs continuously when the above conditions are met. Conditions for Setting the DTC The ECM detects that the pressure difference over the DPF is greater than the set threshold. Action Taken When the DTC Sets DTC P226D is a type A DTC. Conditions for Clearing the DTC DTC P226D is a type A DTC. Reference Information Schematic Reference Engine Controls Schematics Connector End View Reference Master Electrical Component List Electrical Information Reference Circuit Testing Connector Repairs Testing for Intermittent Conditions and Poor Connections Wiring Repairs DTC Type Reference Powertrain Diagnostic Trouble Code (DTC) Type Definitions Scan Tool Reference Control Module References Circuit/System Verification

  1. Ignition » On / Vehicle » In Service Mode
  2. Verify there are no DTCs set related to the following component/system: – B9 Ambient Air Temperature Sensor – B75C Multifunction Intake Air Sensor – B131 Exhaust Temperature Sensor – B154 Diesel Particulate Filter Exhaust Differential Pressure Sensor ⇒ If a related DTC is set Refer to: Diagnostic Trouble Code (DTC) List - Vehicle ⇓ If a related DTC is not set
  3. Verify DTC P226D is not set. ⇒ If the DTC is set Replace the diesel particulate filter. ⇓ If no DTC is set
  4. All OK. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair. Nitrogen Oxides Catalytic Converter with Filter Replacement