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Home >> Chevrolet >> 2024 >> Tahoe Commercial, 4WD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 8 (Engine Controls And Fuel - 3.0L (Lm2) Diesel - Diagnostic Information And Procedures (2 Of 5)) >> Diagnostic Information and Procedures >> DTC P0421 >> Circuit/System Verification

Circuit/System Verification

WARNING: This page is about a different variant/trim than selected.
  1. Verify there are no DTCs set related to the following component/system:
    • B17 Barometric Pressure Sensor
    • B34 Engine Coolant Temperature Sensor
    • B65 Intake Manifold Pressure and Air Temperature Sensor
    • B74 Manifold Absolute Pressure Sensor
    • B75C Multifunction Intake Air Sensor
    • B115 Vehicle Speed Sensor
    • B131 Exhaust Temperature Sensor
    • B154 Diesel Particulate Filter Exhaust Differential Pressure Sensor
    • B195A Nitrogen Oxides Sensor 1
    • Q14 Exhaust Gas Recirculation Valve
    • Q17 Fuel Injector
    • Go to next step: If a related DTC is not set 
  2. 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.
  3. Verify the DTC does not set.
    • If the DTC is set 

      Refer to: Circuit/System Testing

    • Go to next step: If no DTC is set 
  4. All OK.
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