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

Honda Accord 10th Generation (2018-2022)

Error Codes

2-4 hours

Time

medium

Difficulty

medium

Severity

Error Code: P0420

3 min read

565 words

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

Affected Component

Exhaust System

Estimated Time

2-4 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect the battery before starting any electrical work
•Allow the exhaust system to cool before working on it

Symptoms

•Check engine light illuminated
•Decreased fuel efficiency
•Poor engine performance
•Increased emissions
•Unusual exhaust smell (rotten eggs)

Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to confirm P0420 and check for any related codes.
2
Inspect the exhaust system for visible leaks or damage, especially around the catalytic converter and exhaust manifold.
3
Measure the oxygen sensor voltages using a multimeter to ensure they are within the expected range during engine operation.
4
Check the fuel trim levels via the OBD-II scanner to identify any abnormalities indicating fuel mixture issues.
5
Perform a visual inspection of the catalytic converter for physical damage or clogging.
6
Test the vehicle’s emissions using an emissions analyzer if available.

Solution

💡 Expert Tip

For complex repairs like this, consider taking photos at each step. This helps if you need to reverse a step or consult with a mechanic. Also, keep all removed parts organized - you may need to reference them during reassembly.

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
•Socket set
•Torque wrench
•Exhaust gasket scraper

Parts Required

•Oxygen sensor (if faulty)
•Catalytic converter (if necessary)
•Exhaust gaskets

Related Faults

Share this solution

Comments

No comments yet

Be the first to share your thoughts

Back to Generation

Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to confirm P0420 and check for any related codes.
2
Inspect the exhaust system for visible leaks or damage, especially around the catalytic converter and exhaust manifold.
3
Measure the oxygen sensor voltages using a multimeter to ensure they are within the expected range during engine operation.
4
Check the fuel trim levels via the OBD-II scanner to identify any abnormalities indicating fuel mixture issues.
5
Perform a visual inspection of the catalytic converter for physical damage or clogging.
6
Test the vehicle’s emissions using an emissions analyzer if available.

Solution

1. Preparation

Gather tools and parts needed for the repair.
Tools Required: OBD-II scanner, multimeter, socket set, torque wrench, exhaust gasket scraper.
Parts Required: Oxygen sensor (if faulty), catalytic converter (if necessary), exhaust gaskets.
Safety Warnings: Disconnect the battery before starting any electrical work; allow the exhaust system to cool before working on it.

2. Oxygen Sensor Replacement (if found faulty)

Disconnect the Battery
- Remove the negative terminal from the battery to prevent electrical shorts.
Locate and Remove the Oxygen Sensor
- Identify the oxygen sensor (upstream or downstream) based on the diagnostic findings.
- Use a socket wrench to unscrew the sensor from the exhaust pipe or catalytic converter.
Install the New Oxygen Sensor
- Apply anti-seize compound to the threads of the new oxygen sensor.
- Screw the new sensor into place and tighten it to the manufacturer's specifications (typically around 30 ft-lbs).

3. Catalytic Converter Inspection/Replacement (if necessary)

Inspect the Catalytic Converter
- Check for any signs of physical damage, excessive heat discoloration, or rattling sounds inside the converter.
Remove the Old Catalytic Converter
- Use the socket set to remove the bolts securing the catalytic converter to the exhaust system.
- Carefully detach the converter from the exhaust pipe.
Install the New Catalytic Converter
- Position the new catalytic converter in place.
- Secure it with bolts and gaskets, tightening to the manufacturer’s torque specifications (consult repair manual for details).
Reassemble Exhaust System
- Ensure all components are properly aligned and secured.
- Replace any gaskets that were disturbed during removal.