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

Solution

1. Preparation

• Gather tools: OBD-II scanner, multimeter, socket set, torque wrench, and safety glasses.
• Disconnect the vehicle battery to ensure safety while working on electrical components.

2. Inspect and Replace Oxygen Sensors

• Sub-step 1: Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors in the exhaust system.
• Sub-step 2: Using a socket wrench, remove the upstream oxygen sensor.
  • Tools Required: Oxygen sensor socket, torque wrench.
• Sub-step 3: Inspect the sensor for damage or carbon build-up; replace if necessary.
• Sub-step 4: Repeat the removal and inspection for the downstream oxygen sensor.
• Sub-step 5: Install new sensors, ensuring they are tightened to the manufacturer's specifications (typically around 30 Nm).

3. Inspect and Replace the Catalytic Converter (if necessary)

• Sub-step 1: If the oxygen sensors are functioning properly, inspect the catalytic converter for clogs or damage.
• Sub-step 2: Remove the catalytic converter from the exhaust system using a socket set.
  • Tools Required: Socket set, penetrating oil (if bolts are rusted).
• Sub-step 3: Check for internal damage or clogs by looking through it or tapping it; if it’s damaged, replace it with a new unit.
• Sub-step 4: Install the new catalytic converter, ensuring all bolts are tightened to the manufacturer’s torque specifications (typically 40-50 Nm).

4. Reassemble and Test

• Sub-step 1: Reconnect the vehicle battery.
• Sub-step 2: Clear the P0420 code using the OBD-II scanner.
• Sub-step 3: Start the engine and let it reach operating temperature.
• Sub-step 4: Test drive the vehicle to ensure the check engine light does not return.