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HOMESERVICE MANUALSCHEVROLET2019TAHOE LS, 4WD, GAS/ETHANOLREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 95 (ENGINE CONTROLS/FUEL - 1.8L (LUW LWE) - DTC P0010 TO DTC P0420)DIAGNOSTIC INFORMATION AND PROCEDURESDTC P0300-P0304CIRCUIT/SYSTEM TESTING
2019 Chevrolet Tahoe LS, 4WD, Gas/Ethanol

Circuit/System Testing

2019 Chevrolet Tahoe LS, 4WD, Gas/EthanolSECTION Circuit/System Testing
WARNING: This page is about a different car, the 2018 Chevrolet Sonic. However, it is still accessible from the selected car via links, so may be relevant.
  1. Verify the following conditions do not exist:
    • Engine - Vacuum leak
    • Exhaust System - Leaking/Missing components/Restricted
    • Fuel - Contaminated/Dirty/Fill Level = Low - Refer to: Alcohol/Contaminants-in-Fuel Diagnosis
    • Fuel Pressure - High/Low - Refer to: Fuel System Diagnosis
    • Positive Crankcase Ventilation System - Leaking/Incorrect connection/Restricted
    • Spark Plug Boot - Carbon Tracking/ Fluid intrusion/Visible Damage
    • Spark Plug - Carbon Tracking/Fouled/Visible Damage
    • Vacuum Hoses - Kinked/Leaking/Incorrect connection/Restricted
    • If a condition exists 

      Repair or replace as necessary.

    • Go to next step: If no conditions exist 
  2. Ignition/Vehicle - Off
  3. Remove the appropriate component:T8 Ignition Coil - Leave the electrical connector connected.
  4. Install the special tool: J-26792 Ignition Spark Tester @K35 Ignition Coil Module & Ground
  5. Engine - Running
    6. NOTE:

    An erratic or weak spark is considered a no spark condition.

  6. Verify there is spark at the tool.
    • Go to next step: If there is spark 
  7. Ignition/Vehicle - Off
  8. Verify the component specifications are correct:Spark Plug - Gap / Heat Range /Torque - Refer to:Ignition System Specifications
    • If not correct 

      Repair or replace as necessary.

    • Go to next step: If correct 
  9. Swap the two components:Spark Plug - The original component that set the DTC & Another known good component from the vehicle
  10. Engine - Running
  11. Verify the scan tool parameter:Cylinder 1 - 4 Current Misfire Counter = Increments - At the original component location the DTC set.
    • If the parameter value does not increment 

      Replace the component:Spark Plug - The original component that set the DTC

    • Go to next step: If the parameter value increments 
  12. Perform the following procedure/test:Fuel Injector Balance - Refer to: Fuel Injector Diagnosis

    Verify the procedure/test passes.

    • If the procedure/test does not pass 

      Replace the component that failed the test:Q17 Fuel Injector

    • Go to next step: If the procedure/test passes 
  13. Verify the condition does not exist:An engine mechanical condition. - Refer to:Symptoms - Engine Mechanical
    • If a condition exists 

      Repair or replace as necessary.

    • Go to next step: If no condition exists 
  14. All OK.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.