how to fix P0420 code on Honda Pilot Third Generation (2016-present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and secured with wheel chocks.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

1. Locate the oxygen sensors: Identify the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
2. Remove the upstream oxygen sensor:
   • Use an oxygen sensor socket or wrench to unscrew the sensor.
   • Disconnect the wiring harness.
3. Install the new upstream oxygen sensor:
   • Apply anti-seize compound to the threads of the new sensor.
   • Hand-tighten the sensor, then use the wrench to secure it (do not overtighten).
4. Repeat the process for the downstream oxygen sensor.

3. Inspect the Catalytic Converter

1. Visual Inspection: Check for any visible signs of damage, such as dents or corrosion.
2. Temperature Test:
   • Start the engine and allow it to reach operating temperature.
   • Measure the exhaust temperature before the catalytic converter (should be higher than after).
3. Replace the catalytic converter (if necessary):
   • Disconnect the exhaust pipes and any hangers.
   • Remove the old catalytic converter from the exhaust system.
   • Install the new catalytic converter, ensuring proper alignment and securing all connections.

4. Reconnect Battery and Clear Codes

1. Reconnect the negative battery terminal.
2. Use the OBD-II scanner to clear the P0420 code.