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Home/Cars/Honda/Accord/10th Generation (2018-2022)/how to fix P0420 code in Honda Accord 9th Generation (2013-2017)

how to fix P0420 code in Honda Accord 9th Generation (2013-2017)

Honda Accord 10th Generation (2018-2022)

Severity: highDifficulty: mediumError Code: P04202-4 hours
3 min read
562 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 Honda Accord (2013-2017). 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 exhaust system to cool before handling components.

Symptoms

  • •Check engine light illuminated
  • •Decreased fuel efficiency
  • •Poor engine performance or sluggishness
  • •Unusual smells from exhaust
  • •Increased emissions during inspection
  • •Rattling noise from the exhaust system

Diagnostic Steps

  1. 1Scan for error codes using an OBD-II scanner to confirm P0420 and check for additional related codes.
  2. 2Inspect the exhaust system visually for any signs of damage, leaks, or loose connections.
  3. 3Check the oxygen sensors (upstream and downstream) for proper operation and functionality.
  4. 4Measure the voltage output of the upstream and downstream oxygen sensors using a multimeter.
  5. 5Perform a fuel trim analysis to check for any significant deviations.
  6. 6Inspect the catalytic converter for physical damage or clogs by tapping gently and listening for rattling sounds.

Solution

Solution

1. Preparation

  • Gather necessary tools and parts.
  • Disconnect the battery to ensure safety during repairs.

2. Inspect and Replace Oxygen Sensors

  • Tools Required: O2 sensor socket, wrench set, multimeter
  • Remove the upstream oxygen sensor (before the catalytic converter):
    1. Disconnect the electrical connector.
    2. Use the O2 sensor socket to unscrew the sensor.
    3. Install the new upstream sensor and reconnect the electrical connector.
  • Repeat the process for the downstream oxygen sensor (after the catalytic converter) if it shows signs of failure.

3. Inspect and Replace the Catalytic Converter

  • Tools Required: Socket set, torque wrench, gasket scraper, exhaust pipe cutter
  • Safely lift the vehicle and support it on jack stands.
  • Remove the exhaust heat shield if necessary.
  • Unbolt the catalytic converter from the exhaust pipe:
    1. Use a socket set to remove the flange bolts.
    2. Gently tap the converter with a rubber mallet to break any sealant.
  • Install the new catalytic converter:
    1. Place a new gasket on the flange.
    2. Bolt the converter back onto the exhaust system and torque to manufacturer specifications.

4. Reconnect Battery and Clear Codes

  • Reconnect the battery terminals.
  • Use the OBD-II scanner to clear the P0420 code and any other related codes.

5. Test Drive

  • Drive the vehicle for at least 20-30 minutes to allow the computer to monitor the exhaust system and verify that the problem is resolved.

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
  • Wrench set
  • Multimeter
  • Socket set
  • Torque wrench
  • Exhaust pipe cutter

Parts Required

  • Upstream oxygen sensor
  • Downstream oxygen sensor
  • Catalytic converter
  • Exhaust gaskets

Additional Information

Error CodeP0420
Component

Exhaust System

Repair Time

2-4 hours

Difficulty

medium

Severity

high

Tools

7 items

Parts

4 items

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