FAULTBASE
NEWSASKCars
© 2025 FAULTBASE
All rights reserved.
v2.0.0 • Production
ContactPrivacyImpressum
Home/Cars/Honda/Civic/10th Generation (2016-2021)/how to fix P0420 code in Honda Civic 11th Generation (2022-Present)

how to fix P0420 code in Honda Civic 11th Generation (2022-Present)

Honda Civic 10th Generation (2016-2021)

Severity: highDifficulty: mediumError Code: P04202-4 hours
3 min read
516 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 issue in Honda Civic 11th Generation. Step-by-step guide with diagnostic procedures 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 completely before examining the exhaust system.

Symptoms

  • •Check engine light illuminated
  • •Decreased fuel efficiency
  • •Poor acceleration or engine performance
  • •Excessive exhaust emissions
  • •Rattling noise from catalytic converter (if damaged)

Diagnostic Steps

  1. 1Scan the vehicle's OBD-II system for error codes to confirm P0420 and check for any related codes.
  2. 2Inspect the exhaust system visually for leaks, cracks, or loose connections.
  3. 3Test the upstream and downstream oxygen sensors using a multimeter to ensure they are functioning correctly.
  4. 4Measure the temperature difference between the inlet and outlet of the catalytic converter with an infrared thermometer.
  5. 5Check for any exhaust back pressure issues using a pressure gauge, ensuring it falls within specifications.

Solution

Solution

1. Preparation

  • Gather tools and parts necessary for the repair.
  • Ensure the vehicle is parked on a level surface and the engine is cool.
  • Disconnect the negative battery terminal.

2. Inspect and Replace Oxygen Sensors

  1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
  2. Use an O2 sensor socket to carefully remove the upstream oxygen sensor.
  3. Install the new upstream oxygen sensor and tighten it to manufacturer specifications (typically around 30-33 lb-ft).
  4. Repeat the process for the downstream oxygen sensor if needed.

3. Inspect and Replace Catalytic Converter

  1. If the catalytic converter is suspected to be faulty, remove the exhaust heat shield and any necessary brackets.
  2. Disconnect the exhaust pipes from the catalytic converter using a socket set.
  3. Remove the catalytic converter from the exhaust manifold and the mid-pipe.
  4. Install the new catalytic converter, ensuring proper alignment and fitment.
  5. Reattach the exhaust pipes and tighten bolts to manufacturer specifications (typically around 30-40 lb-ft).
  6. Reinstall the exhaust heat shield and associated components.

4. Final Checks

  1. Reconnect the negative battery terminal.
  2. Clear the P0420 code using the OBD-II scanner.
  3. Start the engine and let it idle for a few minutes, checking for leaks around the exhaust connections.

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
  • Multimeter
  • Oxygen sensor socket
  • Socket set
  • Infrared thermometer
  • Exhaust pressure gauge

Parts Required

  • Upstream oxygen sensor
  • Downstream oxygen sensor (if needed)
  • Catalytic converter (if faulty)

Additional Information

Error CodeP0420
Component

Exhaust System

Repair Time

2-4 hours

Difficulty

medium

Severity

high

Tools

6 items

Parts

3 items

Related Faults

Discover similar issues

  1. why is my steering wheel hard to turn on Honda Civic 9th Generation (2012-2015)

    Learn how to diagnose and fix a hard-to-turn steering wheel in Honda Civic 2012-2015. Step-by-step guide with symptoms, diagnostic steps, and repair i...

    Component:Steering
    Symptoms
    • •Check engine light illuminated
    • •Increased steering effort, especially at low speeds
    • +{count} more
  2. how to fix P0420 code on Honda Civic 9th Generation (2012-2015)

    P0420

    Learn how to diagnose and fix P0420 catalytic converter efficiency issue in Honda Civic 2012-2015. Step-by-step guide with diagnostic procedures and r...

    Component:Exhaust System
    Symptoms
    • •Check engine light illuminated
    • •Decreased fuel efficiency
    • +{count} more
  3. how to fix the Bluetooth connectivity issue in Honda Civic 9th Generation (2012-2015)

    Learn how to resolve Bluetooth connectivity issues in Honda Civic 2012-2015. Step-by-step guide with diagnostic steps and solutions.

    Component:Electrical
    Symptoms
    • •Bluetooth device unable to find the Honda Civic system
    • •Previous pairings not recognized or deleted
    • +{count} more
  4. why does my Honda Civic steering wheel vibrate at high speeds

    Learn how to diagnose and fix steering wheel vibration in Honda Civic at high speeds. Step-by-step guide with symptoms, diagnostic steps, and repair i...

    Component:Steering
    Symptoms
    • •Steering wheel vibrates or shakes at speeds above 50 mph
    • •Uneven tire wear visible on the front tires
    • +{count} more
  5. why does my Honda Civic feel like it's losing acceleration power

    Learn how to diagnose and fix loss of acceleration power in Honda Civic. Step-by-step guide with diagnostic procedures and repair instructions.

    Component:Engine
    Symptoms
    • •Check engine light illuminated
    • •Reduced engine power during acceleration
    • +{count} more
  6. why does my Honda Civic shake when I brake?

    Learn how to diagnose and fix brake shaking issues in Honda Civic. Step-by-step guide with symptoms, diagnostic steps, and repair instructions.

    Component:Brakes
    Symptoms
    • •Steering wheel shakes during braking
    • •Brake pedal pulsates or vibrates
    • +{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