FAULTBASE
Error CodesASKCars
© 2026 FAULTBASE
All rights reserved.
v2.0.0 • Production
ContactPrivacyImpressum
What are the signs of a clogged catalytic converter in the 2020 Highlander? - Toyota Highlander
Home/Cars/Toyota/Highlander/Fourth Generation (2020-present)/What are the signs of a clogged catalytic converter in the 2020 Highlander?

What are the signs of a clogged catalytic converter in the 2020 Highlander?

Toyota Highlander Fourth Generation (2020-present)

Error Codes
2-4 hours
Time
medium
Difficulty
medium
Severity
Error Code: P0420
Navigation
ProblemSymptomsDiagnosisSolution
ProblemSymptomsDiagnosisSolution
4 min read
680 words

Problem Statement

Learn about the symptoms, diagnostic steps, and repair instructions for a clogged catalytic converter in a 2020 Toyota Highlander.

Error Code
P0420
Affected Component
catalytic converter
Estimated Time
2-4 hours

Symptoms

  • •Reduced Engine Power
  • •Engine Stalling
  • •Poor Fuel Economy
  • •Check Engine Light
  • •Rattling Noise
  • •Excessive Heat

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

  • •Flashlight
  • •OBD-II Scanner
  • •Backpressure gauge
  • •Infrared thermometer
  • •None (basic observation)

Additional Information

Error Code
P0420
Affected Component
catalytic converter
Estimated Time
2-4 hours
Difficulty
medium
Severity
medium
Tools Required
5 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
Signs of a Clogged Catalytic Converter in a 2020 Toyota Highlander

A clogged catalytic converter can lead to various performance issues in your 2020 Toyota Highlander (Fourth Generation). Here are the common symptoms to look for:

Repair Instructions

If you confirm that the catalytic converter is clogged, follow these steps for replacement:

Tools and Materials Required

  • New catalytic converter (OEM recommended)
  • Jack and jack stands
  • Socket set (metric)
  • Wrench set (metric)
  • Torque wrench
  • Exhaust sealing compound (if required)
  • Safety goggles and gloves
  • Penetrating oil (such as WD-40)

Replacement Steps

  1. Safety First

    • Park the vehicle on a level surface, engage the parking brake, and wear safety goggles and gloves.

  2. Lift the Vehicle

    • Use a jack to lift the front of the Highlander and secure it with jack stands.

  3. Remove Exhaust Components

    • Loosen Bolts: Apply penetrating oil to the bolts connecting the catalytic converter to the exhaust system. Use a socket wrench to loosen and remove these bolts.
    • Disconnect O2 Sensors: Unplug the upstream and downstream O2 sensors (if applicable) from the catalytic converter.

  4. Remove the Catalytic Converter

    • Carefully pull the catalytic converter away from the exhaust system. Be cautious of any remaining gaskets or seals; you may need to replace them.

  5. Install New Catalytic Converter

    • Position the new catalytic converter in place. Install any necessary gaskets or seals.
    • Torque Bolts: Reattach the bolts and tighten them to the manufacturer’s specifications using a torque wrench.

  6. Reconnect O2 Sensors

    • Plug in the upstream and downstream O2 sensors.

  7. Lower the Vehicle

    • Carefully remove the jack stands and lower the vehicle.

  8. Clear Check Engine Codes

    • Use the OBD-II scanner to clear any stored trouble codes.

  9. Test Drive

    • Take the Highlander for a test drive to ensure that the issue has been resolved. Monitor for any warning lights or unusual behavior.
Conclusion

A clogged catalytic converter can significantly affect your vehicle's performance. If you suspect a clog based on the symptoms listed, follow the diagnostic steps to confirm the issue, and if necessary, proceed with the replacement following the outlined repair instructions. Always refer to the vehicle's service manual for specific details related to your Highlander.