1. Check the catalytic converter:
- Inspect the catalytic converter for any physical damage, such as cracks or leaks.
- If the catalytic converter is damaged, it will need to be replaced.
2. Check the oxygen sensors:
- Inspect the oxygen sensors for any damage or contamination.
- Clean the oxygen sensors if they are dirty.
- If the oxygen sensors are damaged, they will need to be replaced.
3. Check the exhaust system:
- Inspect the exhaust system for any leaks or restrictions.
- If the exhaust system is leaking, it will need to be repaired.
4. Reset the trouble code:
- Once you have fixed the problem, reset the trouble code by disconnecting the battery for a few minutes.
If the P0420 code persists after following these steps, it may be necessary to take your vehicle to a qualified mechanic for further diagnosis and repair.
