my Honda Accord's check engine light is on, what does P0420 mean?

Solution

1. Preparation

• Gather tools and parts.
• Disconnect the negative terminal of the battery to ensure safety.
• Allow the exhaust system to cool before working on it.

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream and downstream oxygen sensors.
2. Using a wrench, carefully disconnect the electrical connectors from both sensors.
3. Remove the sensors using an oxygen sensor socket.
4. Install new oxygen sensors by reversing the removal steps, ensuring they are tightened to manufacturer specifications (typically 30-40 ft-lbs).
5. Reconnect the electrical connectors.

3. Inspect and Replace the Catalytic Converter

1. If the oxygen sensors are functioning properly, inspect the catalytic converter for any signs of damage or clogging.
2. Remove the exhaust pipe connected to the catalytic converter (use a socket set for bolts).
3. Detach the catalytic converter from its mounting brackets.
4. Install the new catalytic converter, aligning it properly with the exhaust system.
5. Secure it with the mounting bolts, torquing them to manufacturer specifications (usually around 25-30 ft-lbs).
6. Reattach the exhaust pipe.

4. Clear Codes and Test Drive

1. Reconnect the negative terminal of the battery.
2. Use the OBD-II scanner to clear the P0420 code.
3. Test drive the vehicle for at least 20-30 minutes to ensure the check engine light does not reappear.