FAULTBASE
Error CodesASKCars
© 2026 FAULTBASE
All rights reserved.
v2.0.0 • Production
ContactPrivacyImpressum
What could cause the 2020 Highlander to have a poor fuel economy? - Toyota Highlander
Home/Cars/Toyota/Highlander/Fourth Generation (2020-present)/What could cause the 2020 Highlander to have a poor fuel economy?

What could cause the 2020 Highlander to have a poor fuel economy?

Toyota Highlander Fourth Generation (2020-present)

Error Codes
3-5 hours
Time
medium
Difficulty
medium
Severity
Navigation
ProblemSymptomsDiagnosisSolution
ProblemSymptomsDiagnosisSolution
4 min read
667 words

Problem Statement

Learn how to diagnose and fix poor fuel economy issues in the 2020 Toyota Highlander with our comprehensive guide.

Affected Component
fuel system, air intake system, exhaust system
Estimated Time
3-5 hours

Symptoms

  • •Noticeable drop in fuel efficiency compared to manufacturer specifications.
  • •Engine performance issues such as rough idling or hesitation.
  • •Increased exhaust emissions or strange smells.
  • •Warning lights on the dashboard (e.g., Check Engine Light).

Diagnostic Steps

  1. 1
  2. 2
  3. 3
  4. 4
  5. 5
  6. 6
  7. 7

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
  • •Fuel pressure gauge
  • •Multimeter
  • •Vacuum gauge
  • •Basic hand tools (screwdrivers, wrenches, pliers)
  • •Torque wrench
  • •Air filter and fuel filter replacement if necessary
  • •Cleaning supplies for MAF and throttle body

Additional Information

Affected Component
fuel system, air intake system, exhaust system
Estimated Time
3-5 hours
Difficulty
medium
Severity
medium
Tools Required
8 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
Poor Fuel Economy in 2020 Toyota Highlander: Diagnosis and Solutions

Symptoms:

  • Noticeable drop in fuel efficiency compared to manufacturer specifications.
  • Engine performance issues such as rough idling or hesitation.
  • Increased exhaust emissions or strange smells.
  • Warning lights on the dashboard (e.g., Check Engine Light).
Tools Required
  • OBD-II scanner
  • Fuel pressure gauge
  • Multimeter
  • Vacuum gauge
  • Basic hand tools (screwdrivers, wrenches, pliers)
  • Torque wrench
  • Air filter and fuel filter replacement if necessary
  • Cleaning supplies for MAF and throttle body
Repair Instructions

Step 1: Address Fuel System Issues

  • Fuel Filter Replacement:

    1. Locate the fuel filter (check the owner’s manual).
    2. Relieve fuel pressure by removing the fuel pump fuse and running the engine until it stalls.
    3. Disconnect the fuel lines and replace the filter.
    4. Reconnect the lines and fuse, then turn the key to the 'On' position to prime the fuel system.

  • Fuel Pump & Pressure Check:

    1. Connect a fuel pressure gauge to the fuel rail.
    2. Start the engine and check the pressure against specifications (typically around 40-50 psi).
    3. If pressure is low, consider replacing the fuel pump.

Step 2: Clean or Replace MAF Sensor & Air Filter

  • MAF Sensor Cleaning:

    1. Remove the MAF sensor from the air intake.
    2. Use MAF cleaner to spray the sensor elements.
    3. Reinstall the sensor after drying.

  • Air Filter Replacement:

    1. Open the air filter housing.
    2. Remove the old filter and replace it with a new one.

Step 3: Inspect and Clean Throttle Body

  1. Remove the throttle body from the intake manifold.
  2. Use throttle body cleaner and a soft brush to clean the interior surfaces.
  3. Reinstall the throttle body and reconnect any sensors or hoses.

Step 4: Check the Exhaust System

  • Oxygen Sensor Replacement:

    1. Use a socket wrench to remove faulty oxygen sensors.
    2. Install new sensors and clear the codes using the OBD-II scanner.

  • Catalytic Converter Check:

    1. Conduct a backpressure test to check for blockages.
    2. If blocked, consider replacing the catalytic converter.

Step 5: Tune-Up

  • Spark Plug Replacement:
    1. Remove the ignition coil/plug wire.
    2. Use a spark plug socket to remove old plugs.
    3. Install new plugs with the proper torque specification.
Conclusion

Once all checks and repairs have been completed, reset the vehicle’s ECU using the OBD-II scanner. Take the vehicle for a test drive to monitor fuel economy and ensure that no warning lights reappear. Regular maintenance, proper tire pressure, and mindful driving habits contribute significantly to achieving optimal fuel economy. If issues persist, further investigation by a professional technician may be necessary.