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Home/Cars/Toyota/Highlander/Third Generation (2014-2019)/how to resolve P0420 code on my Toyota Highlander Third Generation (2014-2019)

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

Toyota Highlander Third Generation (2014-2019)

Severity: highDifficulty: mediumError Code: P04202-4 hours
3 min read
600 words

⚠️ Safety Warning

This issue requires immediate attention. If you are not experienced with automotive repairs, consult a professional mechanic. Working on critical systems can be dangerous.

Problem Statement

Learn how to diagnose and fix P0420 catalytic converter issues in a Toyota Highlander (2014-2019). Step-by-step guide with symptoms and solutions.

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 inspecting the exhaust system.

Symptoms

  • •Check engine light illuminated
  • •Decreased fuel efficiency
  • •Rough engine performance
  • •Failed emissions test
  • •Unusual exhaust odors

Diagnostic Steps

  1. 1Scan for error codes using an OBD-II scanner to confirm the P0420 code and check for any additional codes.
  2. 2Inspect the exhaust system for any visible leaks or damage that could affect the catalytic converter's performance.
  3. 3Check the oxygen sensors (pre-catalytic and post-catalytic) to ensure they are functioning correctly.
  4. 4Verify the catalytic converter temperature using a thermometer to compare inlet and outlet temperatures.
  5. 5Perform a visual inspection of the wiring and connectors associated with the oxygen sensors.
  6. 6Check fuel trim readings using the scanner to ensure the engine is operating optimally.

Solution

Solution

1. Preparation

  • Gather tools and parts required for the repair.
  • Disconnect the battery to ensure safety while working on electrical components.

2. Inspect and Replace Oxygen Sensors

  • Tools Required: O2 sensor socket, ratchet, torque wrench, penetrating oil (if needed)
  • Sub-steps:
    1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
    2. Use penetrating oil on the sensor threads if they are rusted or stuck. Allow it to sit for a few minutes.
    3. Disconnect the electrical connectors from both oxygen sensors.
    4. Use an O2 sensor socket to remove both sensors.
    5. Install new sensors in the reverse order. Torque them to the manufacturer’s specifications (typically around 30 lb-ft).

3. Inspect and Replace the Catalytic Converter (if necessary)

  • Tools Required: Socket set, cutting tool (if welded), welding equipment (if needed), jack stands
  • Sub-steps:
    1. Lift the vehicle securely using jack stands.
    2. Inspect the catalytic converter for any physical damage or blockage.
    3. If damaged, remove any bolts or clamps securing the catalytic converter to the exhaust system.
    4. For welded units, use a cutting tool to remove the old converter.
    5. Install the new catalytic converter, ensuring all connections are secure. Torque bolts to manufacturer specifications.
    6. Reconnect any electrical connectors that were disconnected during the process.

4. Clear Codes and Test Drive

  • Tools Required: OBD-II scanner
  • Sub-steps:
    1. Reconnect the battery.
    2. Use the OBD-II scanner to clear the P0420 code from the system.
    3. Start the engine and allow it to reach operating temperature.
    4. Take the vehicle for a test drive to ensure the engine runs smoothly and monitor for return of the check engine light.

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
  • O2 sensor socket
  • Ratchet
  • Torque wrench
  • Penetrating oil
  • Socket set
  • Cutting tool
  • Welding equipment

Parts Required

  • Upstream oxygen sensor
  • Downstream oxygen sensor
  • Catalytic converter

Additional Information

Error CodeP0420
Component

Exhaust System

Repair Time

2-4 hours

Difficulty

medium

Severity

high

Tools

8 items

Parts

3 items

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