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Tahoe / Yukon Service Manual

DTC P28F7

Engine Controls and Fuel - 3.0L LM2 Diesel | Diagnostic Information and Procedures | Document ID: 5509059 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 P28F7 Exhaust Pressure Too High Circuit/System Description For an overview of the component/system, refer to: Exhaust Aftertreatment System Description Conditions for Running the DTC DTCs related to the following system/component = Not Set – B345R Exhaust Pressure Differential Sensor - Exhaust Gas Recirculation – M122 Exhaust Pressure Regulator Valve Engine = Running Engine Torque = Greater than a predefined threshold Ignition and Start Switch Signal = Greater than 11 V Frequency the DTC runs = Continuously — After the running conditions are met Conditions for Setting the DTC Exhaust Gas Recirculation Pressure Sensor = Greater than 80 kPa (11.6 PSI) 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: B115 Vehicle Speed Sensor B345R Exhaust Pressure Differential Sensor - Exhaust Gas Recirculation M122 Exhaust Pressure Regulator Valve ⇒ If a related DTC is set Refer to: Diagnostic Trouble Code (DTC) List - Vehicle ⇓ If a related DTC is not set
  3. Verify the following conditions do not exist: Catalytic Converter - Rear — Restricted Exhaust Flow Control Valve. — Coking / Debris on the component. / Restricted / Stuck Exhaust System — Restricted Nitrogen Oxides Catalytic Converter - Rear — Restricted ⇒ If a condition exists Repair or replace as necessary ⇓ If no condition exists
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data. Verify the DTC does not set. ⇒ If the DTC sets A condition with the system still exists » Refer to step 1 ⇓ If the DTC is not set
  5. All OK. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification