[quadcells]

So the light came back on for P0420 22,000 miles after new installed cat. I reset and about 1,000 miles later comes back on.
Could it be the downstream O2 sensor, also getting P1450, would that be related somehow?
Trying to get insight before going back to the mechanic.

 

[sheila]

Did you ever find and fix the issue that initially killed the 1st cat? May try changing the bank#1 upstream (pre-cat) o2 sensor. P1450 is a fuel tank pressure (FTP) sensor evap code which could be the sensor, purge valve, vent valve, hose, etc. It's mainly a Ford (mfg. specific) code.

 

[quadcells]

No, my mechanic said it was bad. We would reset the light and 100 miles later it would come back on. So he changed it. Everything seemed great until about a month ago. I did have 175,000 miles on it then. I am about to hit 200,000 today.