FAULTBASE
Error CodesASKCars
© 2026 FAULTBASE
All rights reserved.
v2.0.0 • Production
ContactPrivacyImpressum
What should I check if my Highlander’s engine is running rough? - Toyota Highlander
Home/Cars/Toyota/Highlander/Fourth Generation (2020-present)/What should I check if my Highlander’s engine is running rough?

What should I check if my Highlander’s engine is running rough?

Toyota Highlander Fourth Generation (2020-present)

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

Problem Statement

Learn how to diagnose and fix rough engine performance issues in your 2020-present Toyota Highlander with detailed steps and required tools.

Affected Component
Engine
Estimated Time
2-4 hours

Symptoms

  • •Engine misfires (unsteady idle)
  • •Rough acceleration or deceleration
  • •Check Engine light illuminated
  • •Decreased fuel efficiency
  • •Engine stalling

Diagnostic Steps

  1. 1
  2. 2
  3. 3

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
  • •Visual Inspection Tools (flashlight, mirror)
  • •Torque Wrench
  • •Multimeter
  • •Socket Set
  • •Gap Gauge
  • •MAF Cleaner
  • •Throttle Body Cleaner
  • •Soft Cloth
  • •Screwdrivers

Additional Information

Affected Component
Engine
Estimated Time
2-4 hours
Difficulty
medium
Severity
medium
Tools Required
10 items

Related Faults

Loading...

Share this solution

Comments

Sign in to share your thoughts

Sign In

No comments yet

Be the first to share your thoughts

Back to Generation

If your 2020-present Toyota Highlander (XU70) is running rough, there are several potential issues that could be causing this problem. Below are detailed steps to diagnose and address the rough engine performance.

Step 1: Check for Diagnostic Trouble Codes (DTCs)

  1. Tool Required: OBD-II Scanner
  2. Procedure:
    • Connect the OBD-II scanner to the diagnostic port (usually located under the dashboard near the steering column).
    • Turn the ignition to the "ON" position (do not start the engine).
    • Read any stored trouble codes. Note down the codes and their descriptions.

Step 2: Inspect Engine Components

  1. Tool Required: Visual Inspection Tools (flashlight, mirror), Torque Wrench, Multimeter
  2. Procedure:
    • Spark Plugs: Remove and inspect for wear, carbon buildup, or damage.
      • If worn or fouled, replace all spark plugs.
    • Ignition Coils: Check for proper connection and functionality. Test with a multimeter if needed.
    • Air Filter: Inspect for clogging or dirt accumulation. Replace if necessary.
    • Vacuum Leaks: Inspect hoses and connections for cracks or breaks. Use a smoke machine or carburetor cleaner to detect leaks.
    • Fuel System: Check fuel pressure with a fuel pressure gauge; it should meet specified values (refer to service manual).
    • Mass Air Flow (MAF) Sensor: Clean with MAF sensor cleaner if dirty.
    • Throttle Body: Inspect and clean if buildup is present.

Step 3: Check Fuel Quality

  1. Procedure:
    • Ensure you are using the correct octane fuel as recommended by Toyota.
    • If fuel is old or contaminated, replace with fresh fuel.
Repair Instructions

Repairing or Replacing Spark Plugs

  1. Tools Required: Socket Set, Torque Wrench, Gap Gauge
  2. Procedure:
    • Remove ignition coils (if applicable) to access spark plugs.
    • Use a spark plug socket to remove old spark plugs.
    • Check the gap on new spark plugs using a gap gauge and adjust if necessary.
    • Install new spark plugs, tightening to manufacturer specifications with a torque wrench.

Replacing Ignition Coils

  1. Tools Required: Socket Set
  2. Procedure:
    • Disconnect the battery to prevent electrical shorts.
    • Remove the electrical connector from each ignition coil.
    • Unscrew and remove the ignition coils.
    • Install new ignition coils and reconnect the electrical connectors.

Cleaning MAF Sensor and Throttle Body

  1. Tools Required: MAF Cleaner, Throttle Body Cleaner, Soft Cloth, Screwdrivers
  2. Procedure:
    • For MAF Sensor:
      • Disconnect the connector and unscrew the MAF sensor from the intake.
      • Spray MAF cleaner on the sensor elements and allow to dry before reinstalling.
    • For Throttle Body:
      • Disconnect the throttle body from the intake.
      • Use throttle body cleaner and a soft cloth to remove carbon buildup on the butterfly valve and inside the throttle body.
      • Reinstall the throttle body.
Final Steps
  1. Reset the Check Engine Light: Using the OBD-II scanner, clear any codes.
  2. Test Drive: Take the vehicle for a drive to see if the rough running condition persists.
  3. Re-scan for Codes: After the test drive, check for any new codes that may have appeared.
Conclusion

By following these steps, you should be able to diagnose and address the rough running condition in your Toyota Highlander. If the problem persists after all checks and repairs, consider consulting a professional mechanic for further diagnosis.