My engine light is on and my scanner is telling me that it is P0420: Catalyst System Efficiency Below Threshold. Now i looked at the voltage of the O2 sensors and bank 1 sensor 1 is completely blank while bank 1 sensor 2 is giving me readings jumping from .3 to .9. Now i also had a mechanic friend look at it for me and he was saying he got the same readings and that he was getting a low fuel pressure code along with the P0420. I'm wondering if anyone has dealt with this and if you have what you had to replace to fix. I don't want to just start replacing things and not fix the issue. My mechanic friend told me that it could be a bad injector but he was originally leaning towards catalytic converter. I've searched the forums and cant seem to find anyone with a similar issue. Please help!