how to fix P0420 code in Honda CR-V Fifth Generation (2017-2022)

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the exhaust system to cool down.

2. Inspect and Test Oxygen Sensors

• Tools Required: OBD-II scanner, multimeter
• Using the OBD-II scanner, monitor the live data of the upstream (bank 1) and downstream oxygen sensors.
• If readings are out of spec (upstream sensor fluctuates and downstream sensor remains steady), consider replacing the faulty sensor.

3. Check and Repair Exhaust Leaks

• Tools Required: Wrench set, exhaust sealant (if needed)
• Inspect the exhaust manifold, pipes, and catalytic converter for leaks.
• If any leaks are found, replace the damaged gasket or repair the pipe using appropriate exhaust sealant.

4. Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, exhaust pipe cutter, new catalytic converter, gaskets
• Remove the bolts securing the catalytic converter using the socket set.
• Carefully cut the exhaust pipe if the converter is welded in.
• Install the new catalytic converter, ensuring proper alignment and using new gaskets.
• Torque the bolts to the manufacturer’s specification (typically around 30 ft-lbs, but check specific specs).

5. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code from the ECU.
• Start the engine and let it idle for a few minutes.