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Tahoe / Yukon Service Manual

DTC P249C

Engine Controls and Fuel - 3.0L LM2 Diesel | Diagnostic Information and Procedures | Document ID: 5509052 Diagnostic Instructions Perform the Diagnostic System Check prior to using this diagnostic procedure: Diagnostic System Check - Vehicle Review the description of Strategy Based Diagnosis: Strategy Based Diagnosis An overview of each diagnostic category can be found here: Diagnostic Procedure Instructions DTC Descriptor DTC P249C Excessive Time To Enter Closed Loop Reductant Injection Control Circuit/System Description For an overview of the component/system, refer to: Exhaust Aftertreatment System Description Conditions for Running the DTC DTC P10C9, P10CA, P10DA, P10DB, P14FA, P20FF, U010E, U2412, U2626 = Not set DTCs related to the following system/component = Not Set – B194 Reductant Pressure Sensor – G33 Reductant Pump Ignition = On or Engine = Running Ignition and Start Switch Signal = Greater than 11 V Reductant Level = Greater than 3 L (0.8 US Liquid Gal) Frequency the DTC runs = Continuously — After the running conditions are met Conditions for Setting the DTC Reductant Pressure = Not within a calibrated range — For greater than 75 s 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. Ignition » On / Vehicle » In Service Mode
  2. Verify there are no DTCs set related to the following component/system: – B194 Reductant Pressure Sensor – G33 Reductant Pump ⇒ If a related DTC is set Refer to: Diagnostic Trouble Code (DTC) List - Vehicle ⇓ If a related DTC is not set
  3. Verify DTC P249C is not set. ⇒ If the DTC is set Refer to: Circuit/System Testing ⇓ If the DTC is not set
  4. All OK. Circuit/System Testing
  5. Perform the scan tool control function: Reductant Fluid Tank Level Reset — Refer to: Reductant Fluid Tank Level Reset
  6. Verify the scan tool parameter: Reductant Tank Level = 25% or greater ⇒ If not the specified state 2.1. Add 3.8 L (1 US Liquid Gal) of fluid: Reductant 2.2. Ignition » On / Vehicle » In Service Mode 2.3. Repeat the procedure starting at step 1 ⇓ If the specified state
  7. Perform the following procedure/test: Contaminants-in-Diesel Exhaust Fluid Diagnosis. ⇒ If a condition exists Repair as necessary ⇓ If no condition exists
  8. Ignition » On / Vehicle » In Service Mode
  9. Perform the scan tool function: Reductant System Leak Test
  10. Verify a condition does not exist with the component: Q61 Reductant Injector — Leaking Reductant Line(s) — Leaking ⇒ If a condition exists Repair as necessary ⇓ If no condition exists
  11. Perform the following procedure/test: Reductant Fluid Injector Quantity Test ⇒ If the procedure/test does not pass Replace the component that has failed in the test. ⇓ If the procedure/test passes
  12. Perform the scan tool function: Reductant System Leak Test
  13. Verify the scan tool parameter: Reductant Pressure = Greater than 450 kPa (65.3 PSI) ⇒ If 450 kPa (65.3 PSI) or less Replace the component: A38 Reductant Pump and Sensor Assembly ⇓ If greater than 450 kPa (65.3 PSI)
  14. All OK. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification Emission Reduction Fluid Tank Replacement — A38 Reductant Pump and Sensor Assembly Reductant Fluid Injector Replacement