how to fix P0420 code in Honda Civic 9th Generation (2012-2015)

Solution

1. Preparation

• Gather necessary tools and parts.
• Park the vehicle on a flat surface and engage the parking brake.
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Remove the upstream O2 sensor (before the catalytic converter) using the O2 sensor socket.
• Install the new upstream O2 sensor and tighten to the manufacturer's specified torque (usually around 30 ft-lbs).
• Repeat the process for the downstream O2 sensor (after the catalytic converter) if it is faulty.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, exhaust pipe cutter, torque wrench, gasket scraper.
• Remove any heat shields or brackets securing the catalytic converter.
• Cut the exhaust pipe before and after the catalytic converter using an exhaust cutter if necessary.
• Clean the exhaust flanges with a gasket scraper to ensure a good seal.
• Install the new catalytic converter and secure it with new gaskets and bolts, torquing to the specified values.

4. Reconnect Battery and Clear Codes

• Reconnect the battery terminals.
• Use the OBD-II scanner to clear the P0420 code from the system.