how to fix Honda CR-V Sixth Generation (2023-present) P0420 code

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, socket set, jack and jack stands, safety goggles, gloves.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

1. Inspect the Oxygen Sensors:

   • Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
   • Visually inspect for any signs of damage, corrosion, or disconnection.

2. Test the Sensors:

   • Using a multimeter, measure the voltage output of the upstream sensor while the engine is at operating temperature; it should fluctuate between 0.1 to 0.9 volts.
   • If the upstream sensor is faulty (staying constant), replace it.

3. Replace the Downstream Sensor:

   • If the upstream sensor is functioning correctly, repeat the voltage test for the downstream sensor.
   • If the voltage is not fluctuating, replace the downstream oxygen sensor.

3. Inspect and Replace Catalytic Converter

1. Inspect the Catalytic Converter:

   • Check for physical damage, dents, or signs of carbon buildup.
   • If damaged, proceed to replace the catalytic converter.

2. Remove the Old Catalytic Converter:

   • Use a socket set to remove the bolts securing the catalytic converter to the exhaust system.
   • Carefully detach any heat shields if present.

3. Install the New Catalytic Converter:

   • Position the new catalytic converter in place and secure it with the bolts.
   • Follow the manufacturer's torque specifications for the bolts.

4. Reconnect the Oxygen Sensors:

   • Reattach the downstream oxygen sensor to the new catalytic converter if applicable.

4. Final Steps

1. Reconnect the Battery:

   • Reconnect the negative battery terminal and ensure all tools are removed from the engine bay.

2. Clear the Codes:

   • Use the OBD-II scanner to clear the P0420 code from the ECM.

3. Test Drive:

   • Take the vehicle for a test drive to ensure the check engine light does not reappear.