FAULTBASE
NEWSASKCars
© 2025 FAULTBASE
All rights reserved.
v2.0.0 • Production
ContactPrivacyImpressum
Home/Cars/Toyota/Highlander/Third Generation (2014-2019)/how to fix P0420 code on Toyota Highlander Third Generation (2014-2019)

how to fix P0420 code on Toyota Highlander Third Generation (2014-2019)

Toyota Highlander Third Generation (2014-2019)

Severity: mediumDifficulty: mediumError Code: P04202-4 hours
3 min read
526 words

Problem Statement

Learn how to diagnose and fix P0420 code in Toyota Highlander (2014-2019). Step-by-step guide with symptoms, diagnostic steps, and repair instructions.

Error Code
P0420
Component
Exhaust System
Repair Time
2-4 hours

Safety Warnings

  • ⚠Disconnect the battery before working on electrical systems.
  • ⚠Allow the engine to cool before working on the exhaust system to avoid burns.

Symptoms

  • •Check engine light illuminated
  • •Decreased fuel economy
  • •Rotten egg smell from exhaust
  • •Rough engine performance
  • •Failed emissions test

Diagnostic Steps

  1. 1Scan for error codes using an OBD-II scanner to confirm P0420.
  2. 2Inspect the exhaust system for leaks and damaged components.
  3. 3Check the condition of the catalytic converter for physical damage or blockage.
  4. 4Test oxygen sensors using a multimeter to ensure they are functioning correctly.
  5. 5Verify the fuel trim readings with the scanner for any abnormal values.
  6. 6Inspect and clean the Mass Air Flow (MAF) sensor if applicable.

Solution

Solution

1. Preparation

  • Tools Required: OBD-II scanner, socket set, multimeter, torque wrench, jack and jack stands, safety goggles, gloves.
  • Ensure the vehicle is on a level surface and the engine is cool.
  • Disconnect the battery to prevent any electrical issues.

2. Inspect Exhaust System

  • Sub-steps:
    • Raise the vehicle securely using a jack and jack stands.
    • Visually inspect the exhaust system from the engine manifold to the tailpipe for any leaks or damage.
    • Check for loose or broken bolts on the exhaust flanges.

3. Test Oxygen Sensors

  • Sub-steps:
    • Locate the upstream and downstream oxygen sensors on the exhaust system.
    • Disconnect the sensor connectors and use a multimeter to check the voltage output.
    • Replace any oxygen sensors that are not within the normal voltage range (typically between 0.1V to 0.9V for upstream).

4. Replace Catalytic Converter (if necessary)

  • Sub-steps:
    • If the catalytic converter is damaged or clogged, remove it by unscrewing the bolts connecting it to the exhaust system.
    • Install the new catalytic converter, ensuring proper alignment and fitment.
    • Torque the bolts to manufacturer specifications (usually around 30-50 ft-lbs, but check service manual for exact values).

5. Reset the ECM

  • Sub-steps:
    • Reconnect the battery terminals.
    • Use an OBD-II scanner to clear the P0420 code from the ECM.
    • Start the engine and allow it to reach operating temperature.

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
  • Torque wrench
  • Jack and jack stands
  • Safety goggles
  • Gloves

Parts Required

  • New catalytic converter (if needed)
  • Oxygen sensors (as required)

Additional Information

Error CodeP0420
Component

Exhaust System

Repair Time

2-4 hours

Difficulty

medium

Severity

medium

Tools

7 items

Parts

2 items

Related Faults

Discover similar issues

  1. how to fix P0420 code in Toyota Highlander Third Generation (2014-2019)

    P0420

    Learn how to diagnose and fix P0420 exhaust system issue in Toyota Highlander (2014-2019). Step-by-step guide with diagnostic procedures and repair in...

    Component:Exhaust System
    Symptoms
    • •Check engine light illuminated
    • •Decreased engine performance
    • +{count} more
  2. how to troubleshoot Toyota Highlander suspension noise

    Learn how to troubleshoot and fix suspension noise in Toyota Highlander. Step-by-step guide with diagnostic steps and repair instructions.

    Component:Suspension
    Symptoms
    • •Clunking or knocking sounds when driving over bumps
    • •Creaking or squeaking noises during turns
    • +{count} more
  3. how to diagnose a dead battery in my Toyota Highlander Third Generation (2014-2019)?

    Learn how to diagnose and fix a dead battery issue in your Toyota Highlander (2014-2019). Step-by-step guide with symptoms, diagnostic steps, and repa...

    Component:Electrical
    Symptoms
    • •Engine does not crank or starts very slowly
    • •Interior lights are dim or not functioning
    • +{count} more
  4. how to replace the spark plugs in my Toyota Highlander Third Generation (2014-2019)

    Step-by-step guide to replacing spark plugs in a 2014-2019 Toyota Highlander. Learn symptoms, diagnostic steps, and tools required for the repair.

    Component:Engine
    Symptoms
    • •Engine misfires or runs unevenly
    • •Poor acceleration and loss of power
    • +{count} more
  5. how to fix P0171 code in Toyota Highlander Third Generation (2014-2019)

    P0171

    Learn how to diagnose and fix P0171 engine too lean condition in Toyota Highlander (2014-2019). Step-by-step guide with diagnostic procedures and repa...

    Component:Engine
    Symptoms
    • •Check engine light illuminated
    • •Rough idle or stalling
    • +{count} more
  6. what does it mean if my Toyota Highlander shakes when I brake

    Learn how to diagnose and fix shaking during braking in Toyota Highlander. Step-by-step guide with symptoms, diagnostic steps, and repair instructions...

    Component:Brakes
    Symptoms
    • •Shaking or vibration in the steering wheel while braking
    • •Pulsation felt through the brake pedal
    • +{count} more

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