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Home >> Chevrolet >> 2018 >> Suburban 3500 HD LT >> Repair and Diagnosis >> External Pages >> Different car >> Section 2 (Engine Controls And Fuel - 5.3L (L83) Or 6.2L (L86) - DTC P0010 To DTC P0442) >> Diagnostic Information And Procedures >> DTC P0420 Or P0430: Catalyst System Low Efficiency Bank 1 And 2 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2018 GMC Yukon XL, 2018 GMC Yukon, 2018 Chevrolet Tahoe, 2018 Chevrolet Suburban, and 2018 Cadillac Escalade ESV. However, it is still accessible from the selected car via links, so may be relevant.
  1. Verify the conditions listed below do not exist with either catalytic converter :
    • Dents
    • Severe discoloration caused by excessive temperatures
    • Road damage
    • Internal rattles caused by damaged catalyst substrate
    • Restrictions
      • If a condition is found 

        Replace the catalytic converters.

      • Go to next step : If no condition is found 
  2. Verify the conditions listed below do not exist with the exhaust system :
    • Leaks
    • Restrictions
    • Physical damage
    • Loose or missing hardware
      • If a condition is found 

        Repair or replace the component as necessary.

      • Go to next step : If no condition is found 
  3. Verify the conditions listed below do not exist with the appropriate B52B heated oxygen sensor 2 :
    • Not at the correct torque
    • Damage
      • If a condition is found 

        Replace the B52B heated oxygen sensor 2 or repair the condition as necessary.

      • Go to next step : If no condition is found 
  4. Test or replace the catalytic converters.
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