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HOMESERVICE MANUALSCHEVROLET2019TAHOE LS, 4WD, GAS/ETHANOLREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 130 (ENGINE CONTROLS/FUEL - 1.4L (LUV) - DTC P0300 TO DTC P2635 & SYMPTOMS)DIAGNOSTIC INFORMATION AND PROCEDURESDTC P0420CIRCUIT/SYSTEM VERIFICATION
2019 Chevrolet Tahoe LS, 4WD, Gas/Ethanol

Circuit/System Verification

2019 Chevrolet Tahoe LS, 4WD, Gas/EthanolSECTION Circuit/System Verification
WARNING: This page is about a different car, the 2018 Chevrolet Sonic. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition On.
  2. Verify there are no other DTCs set.
    • Go to next step: If no other DTCs are set 
  3. Operate the vehicle within the Conditions for Running the DTC.
  4. Verify the scan tool Catalyst Monitor Not At Idle Test Conditions Met parameter changes to Yes.
    • If Yes is not displayed 

      Refer to step 3.

    • Go to next step: If Yes is displayed 
  5. When the conditions are safe, stop and idle the vehicle in gear if equipped with automatic transmission or neutral if equipped with manual transmission.
  6. Verify the Catalyst Monitor Test Result parameter displays Passed when performing the steps listed below:
    1. Apply the service brake.
    2. Monitor the scan tool Catalyst Monitor Test State parameter. When the parameter indicates Active, the Catalyst Monitor Test is running.
      3. NOTE:

      When the test has completed, the Catalyst Monitor Test Counter parameter will increment by one and the Catalyst Monitor Test Result parameter will indicate Passed, Failed or No Result.

    3. Continue to monitor the parameter. When the parameter indicates Inactive, the Catalyst Monitor Test has completed.
    • If No Result is displayed 

      Repeat steps 3 - 6 until the Test Result parameter indicates Passed or Failed

    • If Failed is displayed 

      Refer to Circuit /System Testing

    • Go to next step: If Passed is displayed 
  7. All OK.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.