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What are the symptoms of a bad ignition coil in the Toyota Highlander Fourth Generation? - Toyota Highlander
Home/Cars/Toyota/Highlander/Fourth Generation (2020-present)/What are the symptoms of a bad ignition coil in the Toyota Highlander Fourth Generation?

What are the symptoms of a bad ignition coil in the Toyota Highlander Fourth Generation?

Toyota Highlander Fourth Generation (2020-present)

Error Codes
2-3 hours
Time
medium
Difficulty
medium
Severity
Navigation
ProblemSymptomsDiagnosisSolution
ProblemSymptomsDiagnosisSolution
4 min read
695 words

Problem Statement

Learn about the symptoms of a bad ignition coil in the Toyota Highlander Fourth Generation and how to diagnose and replace it.

Affected Component
ignition coil
Estimated Time
2-3 hours

Symptoms

  • •Engine Misfire
  • •Reduced Engine Power
  • •Check Engine Light
  • •Poor Fuel Economy
  • •Difficulty Starting
  • •Backfiring
  • •Increased Emissions

Diagnostic Steps

  1. 1
  2. 2
  3. 3
  4. 4
  5. 5

Solution

💡 Expert Tip

For complex repairs like this, consider taking photos at each step. This helps if you need to reverse a step or consult with a mechanic. Also, keep all removed parts organized - you may need to reference them during reassembly.

Verification

After completing the repair, verify that the issue has been resolved:

  • ✓Test the affected component to ensure it functions correctly
  • ✓Check for any error codes or warning lights
  • ✓Monitor the vehicle for a few days to ensure the issue does not recur

Prevention Tips

To prevent this issue from occurring again:

  • •Follow the manufacturer's recommended maintenance schedule
  • •Address warning signs early before they develop into major issues
  • •Use quality parts and fluids recommended for your vehicle
  • •Keep detailed records of all repairs and maintenance

Tools & Equipment Required

  • •OBD-II Scanner
  • •Socket set
  • •Multimeter or ignition coil tester
  • •Torque wrench
  • •Dielectric grease
  • •O-ring lubricant

Additional Information

Affected Component
ignition coil
Estimated Time
2-3 hours
Difficulty
medium
Severity
medium
Tools Required
6 items

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Back to Generation

Symptoms of a Bad Ignition Coil in a 2020-Present Toyota Highlander (Fourth Generation - XU70)

A failing ignition coil can lead to various engine performance issues in your Toyota Highlander. Here are the common symptoms to watch for:

Common Symptoms

  1. Engine Misfire:

    • The engine may experience a rough idle and stuttering during acceleration.
    • The vehicle may shake or vibrate when idling.

  2. Reduced Engine Power:

    • Noticeable loss of power during acceleration.
    • Decreased responsiveness when pressing the accelerator.

  3. Check Engine Light:

    • The check engine light (CEL) may illuminate on the dashboard, indicating a problem with the ignition system.

  4. Poor Fuel Economy:

    • Decreased fuel efficiency due to incomplete combustion.

  5. Difficulty Starting:

    • The engine may crank longer than usual before starting or may fail to start altogether.

  6. Backfiring:

    • Unburned fuel igniting in the exhaust system can cause backfiring sounds.

  7. Increased Emissions:

    • Higher emissions due to unburned fuel reaching the exhaust system.
Step 1: Visual Inspection
  • Tools Required: None
  • Check for visible signs of damage, such as cracks, corrosion, or burnt marks on the ignition coils and surrounding components.
Step 2: Use an OBD-II Scanner
  • Tools Required: OBD-II Scanner
  • Connect the scanner to the OBD-II port.
  • Check for any trouble codes related to the ignition coils (e.g., P0300-P0306 for misfires).
Step 3: Inspect Spark Plugs
  • Tools Required: Socket set
  • Remove the spark plugs and inspect them for wear or damage (e.g., fouling, excessive gap).
  • Replace any worn spark plugs, as they can also cause misfires.
Step 4: Check Ignition Coil Functionality
  • Tools Required: Multimeter or an ignition coil tester
  1. Disconnect the ignition coil from the spark plug.
  2. Use a multimeter to measure the primary and secondary resistance according to the specifications in the service manual (typically, primary resistance should be between 0.4 to 2 ohms and secondary resistance between 5,000 to 15,000 ohms).
  3. If the readings are outside the specified range, the ignition coil may be faulty.
Step 5: Swap Coils
  • If multiple coils are present, swap the suspect coil with a known good one.
  • Clear the trouble codes and take the vehicle for a test drive.
  • If the misfire follows the coil, it confirms the coil is defective.
Repair Instructions
Step 1: Gather Required Tools and Parts
  • Tools Required: Socket set, torque wrench, dielectric grease, O-ring lubricant (if applicable).
  • Parts Required: New ignition coil(s), new spark plugs (if necessary).
Step 2: Replace the Ignition Coil
  1. Turn Off the Engine: Ensure the vehicle is turned off, and the keys are removed from the ignition.
  2. Disconnect the Battery: Remove the negative battery cable to avoid electrical shock.
  3. Access the Ignition Coil:
    • Depending on the engine configuration (4-cylinder or V6), locate the ignition coils on the engine.
    • Remove any engine cover if necessary.
  4. Remove the Old Ignition Coil:
    • Disconnect the electrical connector from the ignition coil.
    • Remove the mounting bolts securing the coil (typically torx or socket screws).
    • Carefully pull the ignition coil out of the spark plug well.
  5. Install the New Ignition Coil:
    • Apply a small amount of dielectric grease to the inside of the boot of the new coil.
    • Insert the new ignition coil into the spark plug well and secure it with the mounting bolts.
    • Reconnect the electrical connector until it clicks into place.
  6. Reinstall Any Engine Covers: If you removed any components for access, reinstall them.
  7. Reconnect the Battery: Attach the negative battery terminal.
Step 3: Test the Vehicle
  • Start the engine and observe its performance.
  • Use the OBD-II scanner to ensure no trouble codes remain.
  • Take the vehicle for a test drive to ensure that the symptoms are resolved.
Conclusion

By following these diagnostic steps and repair instructions, you should be able to identify and replace a faulty ignition coil in your Toyota Highlander. Always refer to the vehicle’s service manual for specific specifications and procedures related to your particular model.