FAULTBASE
Error CodesASKCars
© 2026 FAULTBASE
All rights reserved.
v2.0.0 • Production
ContactPrivacyImpressum
Why is my 2023 Toyota Highlander experiencing poor fuel economy? - Toyota Highlander
Home/Cars/Toyota/Highlander/Fourth Generation (2020-present)/Why is my 2023 Toyota Highlander experiencing poor fuel economy?

Why is my 2023 Toyota Highlander experiencing poor fuel economy?

Toyota Highlander Fourth Generation (2020-present)

Error Codes
medium
Difficulty
medium
Severity
Navigation
ProblemSymptomsDiagnosisSolution
ProblemSymptomsDiagnosisSolution
4 min read
635 words

Problem Statement

Learn how to diagnose and fix poor fuel economy issues in your 2023 Toyota Highlander with step-by-step instructions and required tools.

Affected Component
fuel system, air filter, engine performance

Symptoms

  • •Noticeable decrease in miles per gallon (MPG)
  • •Increased frequency of refueling
  • •Engine performance issues (e.g., rough idling, hesitation during acceleration)
  • •Check Engine Light (CEL) may be illuminated

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

  • •Tire pressure gauge
  • •OBD-II scanner
  • •Digital multimeter
  • •Air filter gauge or inspection light
  • •Basic hand tools (screwdrivers, wrenches, ratchet set)
  • •Fuel pressure gauge

Additional Information

Affected Component
fuel system, air filter, engine performance
Difficulty
medium
Severity
medium
Tools Required
6 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
Possible Causes
  1. Tire Pressure Issues
  2. Air Filter Condition
  3. Fuel System Problems
  4. Engine Performance Issues
  5. Driving Habits
  6. Weight and Load
  7. Electrical Systems and Sensors
Tools Required
  • Tire pressure gauge
  • OBD-II scanner
  • Digital multimeter
  • Air filter gauge or inspection light
  • Basic hand tools (screwdrivers, wrenches, ratchet set)
  • Fuel pressure gauge (for fuel system diagnostics)

Step 1: Check Tire Pressure

  1. Use a tire pressure gauge to measure the pressure in all tires, including the spare if applicable.
  2. Compare the readings with the recommended PSI found on the driver’s door jamb sticker.
  3. Inflate tires to the recommended PSI if they are low.

Step 2: Inspect Air Filter

  1. Open the hood and locate the air filter housing.
  2. Remove the air filter cover using the appropriate hand tools.
  3. Inspect the air filter for dirt and debris. Replace if it appears clogged or dirty.
  4. Reinstall the air filter and cover securely.

Step 3: Scan for Trouble Codes

  1. Connect the OBD-II scanner to the diagnostic port (usually located under the dashboard).
  2. Turn the ignition to the "ON" position (do not start the engine).
  3. Read any stored trouble codes and document them for further investigation.
  4. Clear the codes and test drive the vehicle to see if any reappear.

Step 4: Inspect Fuel System

  1. Check the fuel pressure using a fuel pressure gauge. Refer to the service manual for the correct specifications.
  2. If fuel pressure is low, inspect the fuel pump, fuel filter, and fuel injectors for clogs or malfunctions.
  3. Replace the fuel filter if it hasn’t been changed per the maintenance schedule (usually every 30,000 miles).

Step 5: Evaluate Engine Performance

  1. Conduct a visual inspection of the engine bay for any signs of wear or damage to hoses, belts, and connections.
  2. Listen for any abnormal noises (knocking, ticking) that could indicate engine problems.
  3. Check the spark plugs for wear. If they are worn or fouled, replace them.

Step 6: Analyze Driving Habits

  • Assess your driving style. Aggressive acceleration, hard braking, and excessive idling can negatively impact fuel economy.
  • Consider adopting a smoother driving style to see if fuel economy improves.

Step 7: Check Vehicle Load

  • Ensure that unnecessary items are not stored in the vehicle, which can add weight and affect fuel economy.
  • Remove any roof racks or carriers if they are not in use.
Repair Instructions

Fuel System Repairs

  1. Replacing Fuel Filter:

    • Relieve fuel system pressure before starting (refer to the service manual).
    • Disconnect the battery.
    • Remove the old fuel filter and install the new one, ensuring correct orientation.
    • Reconnect the battery and check for leaks.

  2. Replacing Spark Plugs:

    • Disconnect the ignition coils and remove them to access the spark plugs.
    • Use a spark plug socket to remove old plugs and replace them with new ones.
    • Reassemble the ignition coils and reconnect.

Air Filter Replacement

  • Simply remove the old air filter from the housing and insert the new one, ensuring a snug fit before reattaching the cover.
Conclusion

After performing the above diagnostics and repairs, monitor the fuel economy over the next few weeks. If the issue persists despite addressing all potential causes, consider consulting a certified Toyota technician for a deeper inspection, as it may involve more complex issues like transmission problems or advanced electronic control system malfunctions.