So in March, CEL came on, bank 1 sensor 1. Dealer tossed one in. Perfect.

july 3, p0151 I THINK... it was Bank 2 sensor 1. Dealer tossed one in.

Today, p0420 shows up. Go to a friends shop, he says replace both rear 02s because they just may be on the way out. He said if he was going to do a cat he’d do the sensor too.

Im thinking Sensor 1 bank 1 may be bad. Look at the exhaust gas readings! Am I wrong?


Check out the difference between exhaust gases...

 

I am working on code P0430 for my 2011 3.5 Explorer. I have read everything I can find on this and the first and easiest recommendation I have found is to replace the downstream O2 sensors. I went ahead and replaced both sensors with no change in the code or data. There are a couple of threads online where owners found an exhaust leak within a few inches downstream of the sensor that was triggering the code. I could not find any small cracks or hear an exhaust leak so I had a smoke test performed that didn't find anything. I ordered a new downstream cat and plan to install this weekend. I'll let you know if it works.

 

I’ll be honest, I replaced the 02, and I got another p0420 I think. I was told to replace the cat with all the 02 sensors. I replaced the other 3 and it’s been okay. I used Ford parts.