why does my check engine light keep coming on 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

526 words

Problem Statement

Learn how to diagnose and fix P0420 engine issues in Honda Accord 2013-2017. Step-by-step guide with diagnostic procedures and repair instructions.

Error Code

P0420

Affected Component

Engine

Estimated Time

2-4 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect the battery before working on electrical systems.
•Allow the engine to cool before inspecting components to avoid burns.

Symptoms

•Check engine light illuminated
•Rough engine idle
•Decreased fuel efficiency
•Engine stalling during acceleration
•Unusual engine noises
•Emissions test failure

Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to identify specific trouble codes.
2
Inspect the gas cap for proper sealing and signs of wear or damage.
3
Check engine oil and coolant levels; look for any leaks around the engine.
4
Examine the air intake system for obstructions or leaks.
5
Test the battery voltage and connections for any signs of corrosion or weakness.
6
Inspect spark plugs and ignition coils for wear or damage.

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
•Spark plug socket
•Wrench set
•Torque wrench
•Multimeter

Parts Required

•Spark plugs (OEM recommended)
•Oxygen sensors (if faulty)
•Engine oil (if needed for checks)

Related Faults

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Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to identify specific trouble codes.
2
Inspect the gas cap for proper sealing and signs of wear or damage.
3
Check engine oil and coolant levels; look for any leaks around the engine.
4
Examine the air intake system for obstructions or leaks.
5
Test the battery voltage and connections for any signs of corrosion or weakness.
6
Inspect spark plugs and ignition coils for wear or damage.

Solution

1. Preparation

Gather tools and parts required for the repair.
Disconnect the battery to ensure safety while working on electrical components.

2. Address Fault Codes

Refer to the OBD-II scanner results and prioritize the repairs needed based on the fault codes.
For example, if a P0420 (Catalytic Converter Efficiency Below Threshold) code appears:
1. Inspect the catalytic converter for physical damage.
2. Check the oxygen sensors for proper operation and replace if faulty.

3. Inspect and Replace Spark Plugs

Remove the ignition coils (if applicable) to access the spark plugs.
Use a spark plug socket to remove the old spark plugs.
Inspect the old plugs for wear; if needed, replace with OEM-spec plugs.
Torque new spark plugs to manufacturer specifications, usually around 13 lb-ft.

4. Replace Oxygen Sensors (if faulty)

Locate the oxygen sensors using the vehicle’s repair manual.
Disconnect the electrical connector and use a wrench to remove the sensor.
Install the new oxygen sensor and secure it, ensuring proper torque (typically around 30 lb-ft).
Reconnect the electrical connector.

5. Recheck and Clear Codes

Reconnect the battery.
Use the OBD-II scanner to clear any fault codes.
Start the engine and verify that the check engine light has turned off.