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Home >> Chevrolet >> 2018 >> City Express LS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls And Fuel - 2.0L >> Diagnostic Information And Procedures >> DTC P0420 >> Circuit/System Verification
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Circuit/System Verification

  1. Ignition ON.
  2. Verify that no other DTC is set.
    • Go to next step: If DTC is not set 
  3. Inspect the catalyst for the following conditions:
    • Dents
    • A discoloration of the catalyst caused by higher temperatures
    • Road damage
    • An internal rattle caused by damaged catalyst substrate
    • Restrictions
    • If a condition is found 

      Replace the catalyst.

    • Go to next step: If no condition is found 
  4. Inspect the exhaust system for the following conditions:
    • Leaks
    • Physical damage
    • Loose or missing hardware
    • Restrictions
    • If a condition is found 

      Repair the exhaust system.

    • Go to next step: If no condition is found 
  5. Inspect the B52B Heated Oxygen Sensor 2 for the following conditions:
    • A grounded wiring harness
    • Damage
    • If a condition is found 

      Replace the B52B Heated Oxygen Sensor 2.

    • Go to next step: If no condition is found 
  6. Refer to Circuit/System Testing  .
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