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Home/Cars/Honda/Accord/9th Generation (2013-2017)/how to fix my Honda Accord's P0420 code

how to fix my Honda Accord's P0420 code

Honda Accord 9th Generation (2013-2017)

Severity: highDifficulty: mediumError Code: P04202-4 hours
3 min read
527 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. 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 inspection or repairs to avoid burns.

Symptoms

  • •Check engine light illuminated
  • •Decreased fuel efficiency
  • •Rough engine idle
  • •Failed emissions test
  • •Unusual exhaust odor (sulfur or rotten egg smell)

Diagnostic Steps

  1. 1Scan the vehicle’s onboard computer using an OBD-II scanner to confirm the P0420 code.
  2. 2Inspect the exhaust system for any visible leaks or damage, especially before and after the catalytic converter.
  3. 3Check the oxygen sensors (upstream and downstream) for proper operation using a multimeter or scan tool.
  4. 4Evaluate the catalytic converter for physical damage or blockage, and check for rattling sounds when tapped lightly.
  5. 5Inspect exhaust gas temperature before and after the catalytic converter to ensure it is functioning correctly.

Solution

Solution

1. Preparation

  • Tools Required: OBD-II scanner, socket set, torque wrench, multimeter, jack and jack stands.
  • Disconnect the battery to ensure safety while working on the electrical components.

2. Inspect and Replace Oxygen Sensors

  • Sub-steps:
    1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
    2. Use a socket to remove the upstream O2 sensor and inspect its condition. Replace if it's damaged or corroded.
    3. Repeat for the downstream O2 sensor.
    4. Install new sensors and torque to manufacturer specifications (usually around 30 lb-ft).

3. Examine and Replace Catalytic Converter

  • Sub-steps:
    1. If the catalytic converter is determined to be faulty, lift the vehicle using a jack and secure it with jack stands.
    2. Remove the bolts connecting the catalytic converter to the exhaust system using a socket set.
    3. Carefully detach the catalytic converter and inspect the gaskets for wear. Replace if necessary.
    4. Install the new catalytic converter and secure it with bolts. Torque to manufacturer specifications (typically around 25 lb-ft).
    5. Replace any gaskets or seals to ensure a proper seal.

4. Reconnect Battery and Clear Codes

  • Reconnect the battery terminals.
  • Use the OBD-II scanner to clear the P0420 trouble code from the vehicle’s memory.

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
  • Torque wrench
  • Multimeter
  • Jack and jack stands

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

5 items

Parts

4 items

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