i just received a check engine light with a p0420 code . where do I start?

 

Catalytic Converter

 

I think P0420 is bank 1 so passenger side. Maybe start with o2 sensors cause that's a lot cheaper than new cats (I just priced out new cats for my 05 and my head almost exploded after the quote with labor).

 

Its the passenger side cat. You can get a direct fit magna flow bolt on replacement for around $300 I believe.

 

The cat is NOT where to start. Misfires (common problem on these trucks) dump unburned fuel into the exhaust that can 'overwhelm' the cat's ability to burn it all off and result in Cat inefficiency code. Also a vacuum leak will drive fuel trims positive - and usually you'd get a lean code first - but if the cat is weak (but still quiet workable) you could get a cat inefficiency code first. Also - a cat that has produced an efficiency code will 'heal' if another problem was causing it and gets corrected before you KILL the cat. That happened to mine back over 100,000 miles ago. Got rid of misfires and other problems (timing job) and she's going strong at 250k. Cat's work fine.

 

I'm not the OP but this was very helpful info. I'm troubleshooting what sounds like pinging (no codes yet) and bad cats were on my list of suspects. Thanks F150Torqued!