Ok so I have a 2000 runner ltd, and I have finally fixed the PO171 code ( dirty MAF sensor ) and now I have a new code PO 420, bank1 and I have CA emissions. My manual says it could be 3-way Cat Converter problem,open/short HO2S Circuit, HO2S Failure or A/F sensor Bank 1 sensor1. Would any of those issues be related to my previous code? And does anyone know of a do it yourself fix for this code that I can try before I have to take my truck to a mechanic? Any suggestions will be helpful!

 

I have a 2000 4 Runner Limited and had the CE light (P0420 code) come on. I brought it to my mechanic and after testing the exhaust system recommended replacement of entire system from the manifold back. He used after market cats and after $ 1600 buckeroos low and behold the light was still on. (same code). After several attempts to fix the problem he seemed to think I would need to use Toyota OEM cats. (another $ 2000 buckeroos) eeeeeek. Fortunately I am a CPA and decided to check with several of my clients in the auto business for a list of possible remedies in order of cost. Cleaning the fuel injectors was on the list and in the end that's all it needed. Now I am left wondering if maybe he should have tried that before replacing the cats.