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Home/Cars/Honda/Accord/9th Generation (2013-2017)/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 9th Generation (2013-2017)

Severity: highDifficulty: mediumError Code: P04202-4 hours
3 min read
526 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 9th Generation (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 inspecting or working on the exhaust system.

Symptoms

  • •Check engine light illuminated
  • •Decreased fuel efficiency
  • •Rough idle or stalling
  • •Increased exhaust emissions
  • •Unusual engine noises (e.g., rattling from the catalytic converter)

Diagnostic Steps

  1. 1Scan for error codes using an OBD-II scanner to confirm the P0420 code.
  2. 2Inspect the exhaust system for any visible leaks or damage.
  3. 3Check the condition and operation of the upstream and downstream oxygen sensors.
  4. 4Measure the voltage output of the oxygen sensors using a multimeter.
  5. 5Inspect the catalytic converter for physical damage or blockage.
  6. 6Verify the fuel trim readings to check for fuel delivery issues.

Solution

Solution

1. Preparation

  • Gather tools and parts.
  • Ensure the vehicle is parked on a level surface and the engine is cool.
  • Disconnect the negative battery terminal to prevent electrical shock.

2. Inspect and Replace Oxygen Sensors

  1. Locate the Oxygen Sensors

    • Identify the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Remove the Oxygen Sensors

    • Use an oxygen sensor socket to carefully unscrew and remove the sensors.
    • Note the orientation for reinstallation.
  3. Install New Oxygen Sensors

    • Apply anti-seize compound to the threads of the new sensors.
    • Install the new sensors and torque them to manufacturer specifications (typically around 30 ft-lbs).

3. Inspect and Replace Catalytic Converter (if necessary)

  1. Inspect Catalytic Converter

    • Check for physical damage, rattling sounds, or excessive heat.
    • If damaged, proceed with replacement.
  2. Remove the Old Catalytic Converter

    • Use a socket set to unbolt the catalytic converter from the exhaust system.
    • Carefully remove any heat shields and gaskets.
  3. Install New Catalytic Converter

    • Position the new catalytic converter in place.
    • Use new gaskets and bolts, tightening to the manufacturer’s torque specifications (typically around 30-35 ft-lbs).

4. Reset the Check Engine Light

  • Reconnect the negative battery terminal.
  • Use the OBD-II scanner to clear the P0420 code.

5. Test the System

  • Start the engine and allow it to reach operating temperature.
  • Perform a test drive to ensure the check engine light remains off.

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
  • Oxygen sensor socket
  • Socket set
  • Torque wrench
  • Multimeter

Parts Required

  • Upstream oxygen sensor
  • Downstream oxygen sensor
  • Catalytic converter (if necessary)
  • 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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