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Home >> Chevrolet >> 2021 >> Trailblazer RS, 4WD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 9 (Engine Controls And Fuel - 1.0L (L4B L4F L4G LIJ) Or 1.2L (L4H L4K LIF LIH) - Diagnostic Information And Procedures (1 Of 2)) >> Diagnostic Information and Procedures >> DTC P0171 or P0172 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.

P0171

  1. Ignition/Vehicle - Off
  2. Verify the following conditions do not exist:
    • B75C Multifunction Intake Air Sensor - Contamination of the measuring element/Skewed/Water intrusion
    • Q17 Fuel Injector - Restricted - Refer to Fuel Injector Diagnosis
    • Air Cleaner Element - Incorrect/Missing
    • Engine - Vacuum leak
    • Evaporative Emission Canister - Cracked/Leaking/Visible Damage
    • Exhaust System - Leaking/Missing components - Refer to Symptoms - Engine Exhaust
    • Fuel - Contaminated/Poor Quality - Refer to Alcohol/Contaminants-in-Fuel Diagnosis
    • Fuel level - Low
    • Fuel Pressure - Low - Refer to Fuel System Diagnosis
    • Intake Manifold - Vacuum leak
    • Intake Air Duct - Cracked/Leaking/Loose Clamps/Visible Damage
    • Oil Filler Cap - Leaking/Missing
    • Positive Crankcase Ventilation System - Incorrect connection/Leaking/Restricted
    • Vacuum Hoses - Incorrect connection/Kinked/Leaking/Restricted
    • If a condition exists 

      Repair or replace as necessary

    • Go to next step: If no condition exists 
  3. All OK.

P0172

  1. Ignition/Vehicle - Off
  2. Verify the following conditions do not exist:
    • B75C Multifunction Intake Air Sensor - Contamination of the measuring element
    • Q17 Fuel Injector - Leaking - Refer to Fuel Injector Diagnosis
    • Q38 Throttle Body - Blocked/Coking/Restricted
    • Air Cleaner Element - Dirty/Restricted/Saturated with water
    • Evaporative Emission Canister - Missing components/Saturated with fuel/Visible Damage
      • NOTE:

      If a condition exists - Replace the component: Engine Oil

    • Excessive fuel in the crankcase - Verify the condition does not exist with the component and repair as necessary:
    • Exhaust System/Catalyst System - Leaking/Missing components/Restricted/Severe discoloration caused by excessive temperatures/Visible Damage - Refer to Symptoms - Engine Exhaust
    • Fuel - Contaminated/Poor Quality - Refer to Alcohol/Contaminants-in-Fuel Diagnosis
    • Fuel Pressure - High - Refer to Fuel System Diagnosis
    • Intake Air Duct - Collapsed/Restricted/Visible Damage
    • If a condition exists 

      Repair or replace as necessary

    • Go to next step: If no condition exists 
  3. All OK.
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