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Home >> Chevrolet >> 2018 >> Equinox L >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 13 (Engine Controls And Fuel - 1.6L (LH7) Diesel - Diagnostic Information And Procedures (P0016 - P049D)) >> Diagnostic Information And Procedures >> DTC P0421: Catalyst 1 Low Efficiency >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.
  1. Verify the following conditions do not exist with the air induction system and exhaust system:
    • Induction system leaks.
    • Exhaust leaks before or after the diesel oxidation catalyst. Refer to Exhaust Leakage for further diagnosis.
    • Physical damage.
    • Loose or missing hardware.
    • If a condition is found 

      Repair or replace the affected exhaust system components as necessary.

    • Go to next step: If no condition is found 
  2. Verify the following conditions do not exist with the diesel oxidation catalyst:
    • Physical damage or alterations.
    • Internal rattles caused by a damaged catalyst substrate.
    • Restrictions.
    • If a condition is found 

      Replace the diesel oxidation catalyst.

    • Go to next step: If no condition is found 
  3. Verify the following conditions do not exist:
    • Off road fuel or red dye fuel.
    • Low quality B20 fuel.
    • Fuel containing high sulfur content.
    • Engine oil or coolant consumption.
    • If a condition is found 

      Repair as necessary.

    • Go to next step: If no condition is found 
  4. Replace the component: B131B Exhaust Temperature Sensor 2 & diesel oxidation catalyst
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