what causes my Honda CR-V to have a check engine light and P0420 code

Solution

1. Preparation

• Gather tools and parts needed for the repair, including new oxygen sensors if necessary.
• Ensure the vehicle is parked on a level surface and the engine is cool.

2. Inspect and Replace Oxygen Sensors

1. Disconnect the Battery

   • Use a socket set to remove the negative battery terminal. This prevents electrical shorts during repairs.

2. Remove the Oxygen Sensors

   • Locate the upstream and downstream oxygen sensors. Use an oxygen sensor socket or wrench to carefully unscrew them from the exhaust system.
   • Note the orientation and connector type for reinstallation.

3. Install New Oxygen Sensors

   • Apply anti-seize compound to the threads of the new oxygen sensors (if recommended).
   • Install the new sensors and torque them to the manufacturer's specifications (typically around 30 lb-ft).
   • Reconnect the wiring harness to the sensors.

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

1. Remove the Exhaust System Components

   • Use a socket set to unbolt any heat shields or exhaust pipes connected to the catalytic converter.
   • Carefully detach the catalytic converter from the exhaust manifold and the downstream exhaust pipe.

2. Install the New Catalytic Converter

   • Position the new catalytic converter in place and secure it using the original or new gaskets.
   • Torque the bolts to manufacturer specifications, ensuring a secure fit without leaks.

3. Reassemble Exhaust Components

   • Reattach any heat shields or additional exhaust components that were removed.
   • Ensure all connections are tight and secure.