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Home >> Chevrolet >> 2021 >> Blazer RS, FWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 12 (Engine Controls And Fuel - 2.0L (LSY) - Diagnostic Information And Procedures (2 Of 2)) >> Diagnostic Information and Procedures >> DTC P0420 >> Circuit/System Verification

Circuit/System Verification

WARNING: This page is about a different variant/trim than selected.
  1. Ignition - On/Vehicle - In Service Mode
  2. Verify there are no DTCs set related to the following component/system:
    • B34 Engine Coolant Temperature Sensor
    • B52 Heated Oxygen Sensor
    • B74 Manifold Absolute Pressure Sensor
    • B75B Mass Air Flow/Intake Air Temperature Sensor
    • B106 Throttle Position Sensor
    • B150 Fuel Tank Pressure Sensor
    • B198 Fuel Composition Sensor
    • Q17 Fuel Injector
    • Engine Misfire
    • Evaporative Emission (EVAP) System
    • Fuel Trim System
    • Go to next step: If a related DTC is not set 
  3. Verify the following conditions do not exist:
    • If a condition exists 

      Repair or replace as necessary

    • Go to next step: If no condition exists 
  4. Verify a condition does not exist with the component: B52 Heated Oxygen Sensor - Loose/Poor Connection/Visible Damage
    • If a condition exists 

      Repair or replace as necessary

    • Go to next step: If no condition exists 
  5. Verify a condition does not exist with the component: Exhaust System & Catalytic Converter
    • Cracked
    • Internal component rattle
    • Leaking - Refer to: Exhaust Leakage
    • Loose Clamps
    • Missing components
    • Restrictions
    • Severe discoloration caused by excessive temperatures
    • Visible Damage
    • If a condition exists 

      Repair or replace as necessary

    • Go to next step: If no condition exists 
  6. Replace the component: Catalytic Converter