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Home/Cars/Honda/Accord/Eleventh Generation (2023-present)/how to fix P0420 code on Honda Accord 9th Generation (2013-2017)

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

Honda Accord Eleventh Generation (2023-present)

Severity: highDifficulty: mediumError Code: P04202-4 hours
3 min read
554 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 exhaust system issue 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 engine to cool before working on the exhaust system.

Symptoms

  • •Check engine light illuminated
  • •Decreased fuel efficiency
  • •Rough engine idle
  • •Failed emissions test
  • •Unusual smells from the exhaust

Diagnostic Steps

  1. 1Scan for error codes using an OBD-II scanner to confirm the P0420 code and check for any related codes.
  2. 2Inspect the exhaust system visually for leaks or damage.
  3. 3Check the upstream and downstream oxygen sensors for proper operation and condition.
  4. 4Measure the voltage output of the oxygen sensors at various engine RPMs.
  5. 5Inspect the catalytic converter for physical damage or signs of clogging.
  6. 6Test the vehicle's fuel trim readings to ensure they are within normal ranges.

Solution

Solution

1. Preparation

  • Gather necessary tools and parts.
  • Park the vehicle on a level surface and engage the parking brake.
  • Disconnect the negative battery terminal to ensure safety.

2. Inspect and Replace Oxygen Sensors

  • Tools Required:

    • O2 sensor socket or wrench
    • Torque wrench
  • Sub-steps:

    1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
    2. Disconnect the electrical connectors from both sensors.
    3. Use the O2 sensor socket to remove the sensors.
    4. Install the new oxygen sensors, ensuring they are torqued to the manufacturer's specifications (typically around 30 ft-lbs).
    5. Reconnect the electrical connectors.

3. Inspect and Replace Catalytic Converter

  • Tools Required:

    • Jack and jack stands
    • Socket set
    • Exhaust gasket
    • Torque wrench
  • Sub-steps:

    1. Raise the vehicle using a jack and secure it with jack stands.
    2. Disconnect the exhaust pipe from the catalytic converter by removing the bolts.
    3. Remove any heat shields if present.
    4. Detach the catalytic converter from the exhaust manifold or pipe.
    5. Install the new catalytic converter with an exhaust gasket, ensuring proper alignment.
    6. Reattach the exhaust pipe and tighten all bolts to the specified torque (check the service manual for exact values).

4. Final Check

  • Reconnect the negative battery terminal.
  • Start the engine and let it idle for a few minutes to check for leaks and proper operation.

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 or wrench
  • Torque wrench
  • Jack and jack stands
  • Socket set

Parts Required

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

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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