how to fix P0420 code on my Honda Pilot YF3 (2016-2022)

Solution

1. Preparation

• Gather tools: OBD-II scanner, socket set, multimeter, exhaust thermometer, safety glasses, gloves.
• Disconnect the negative battery cable to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

1. Remove the upstream oxygen sensor:
   • Locate the upstream oxygen sensor (typically before the catalytic converter).
   • Use a socket or wrench to unscrew the sensor.
2. Install the new upstream oxygen sensor:
   • Apply anti-seize compound on the threads of the new sensor.
   • Screw in the new sensor and tighten to the manufacturer's specifications (typically around 30 ft-lbs).
3. Repeat for the downstream oxygen sensor:
   • Locate and remove the downstream sensor.
   • Install the new sensor using the same procedure as above.

3. Inspect and Replace Catalytic Converter (if needed)

1. Remove the catalytic converter:
   • Remove any heat shields or brackets securing the catalytic converter.
   • Unscrew the bolts or nuts connecting the catalytic converter to the exhaust pipes.
2. Install the new catalytic converter:
   • Position the new catalytic converter in place.
   • Reattach and tighten all bolts/nuts to the manufacturer's specifications.
3. Reinstall heat shields and brackets.

4. System Reset

1. Reconnect the battery:
   • Ensure the battery is connected properly.
2. Clear error codes:
   • Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.