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Tahoe / Yukon Service Manual

DTC P244C

Engine Controls and Fuel - 3.0L LM2 Diesel | Diagnostic Information and Procedures | Document ID: 5508896 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 P244C Catalytic Convertor Low Temperature During Regeneration Circuit/System Description For an overview of the component/system, refer to: Exhaust Aftertreatment System Description The diesel exhaust aftertreatment system consists of an under hood pre-catalytic converter and an underbody catalyst converter. The underbody catalyst converter also consists of the main Diesel Oxidation Catalyst and the coated Diesel Particulate Filter (DPF). One of the main purposes 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 The DTC runs during the DPF regeneration process. Conditions for Setting the DTC The exhaust gas temperature is too low during regeneration. Actions Taken When the DTC Sets DTCs listed in the DTC Descriptor category = Type A DTC Conditions for Clearing the DTC DTCs listed in the DTC Descriptor category = 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. Verify the integrity of the entire air induction system and exhaust system, including all turbocharger components by inspecting for the conditions listed below: Leaks or restrictions in the hoses and pipes to the B136 Exhaust Differential Pressure Sensor Damage to induction system components, including the turbocharger and charge air cooler Loose or improperly installed components Air flow restrictions Exhaust leaks, including the mating surface between the turbocharger and exhaust manifold ⇒ If a condition is found Repair as necessary ⇓ If no condition is found
  2. Perform the Diesel Particulate Filter Service Regeneration. Particulate Filter Service Regeneration
  3. Verify the regeneration completed. ⇒ If the regeneration did not complete Replace the Diesel Particulate Filter ⇓ If the regeneration completed
  4. All OK. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification Nitrogen Oxides Catalytic Converter with Filter Replacement — Particulate Filter Additional Procedures Particulate Filter Reset — Perform only when the following component/system is replaced or serviced: Particulate Filter — Replaced