Hello All,

I got the code P0420 on my Civic and while driving I would get sudden power loss. I was told it was my Catalytic Converter...so I replaced it with a new one. At first my car started after installing it, then when driving it home. Now it wont start again. Any ideas what it can be. PS bought and replaced spark plugs, ignition coil, and distributor like 3 months ago. Car also cranks on correct timing just no start.

 

Possible causes are:
1. Three way cat. deterioration
2. Exhaust system leak.

Since you just replaced the cat, check for a leak upstream of the O2 sensor.