I have a 2004 Ford F150 XLT 4x4, 5.4L - v8 with just a few miles on it... 248k and still going strong. I started recieving the P0430 code and replaced all 4 of the original OEM O2 sensors with 4 Bosch 15664 sensors. It seems that after I reset the code the truck runs great but after about 2.5days the engine light comes back on. I am not seeing any physical indication the the cats are bad. What am I missing or where else should I be looking to get this problem resolved? Any information that can be given to correct it is greatly appreciated.

 

did you ever figure out your problem? I am experiencing the exact same thing now.

 

What I found out is that I had a Cat that was bad. I had the Driver's Side Cat replaced and have had no more issues since. I hope this helps.