Catalyst System Efficiency Below Threshold (Bank 1)

Now that is the O2 sensor after the Cat, right?

 

yes. highflow? gutted? sim?

 

stock cat, plus while driving the light went off by itself.

 

You might have an o2 sensor goofing up. The catalytic converter could be the culprit. Get your hands on an infrared thermometer and take two temprature readings at the converter one in front and one in the back. There should be 100 degrees difference between the inlet and outlet witht the car running and hot. If there is 100 degrees or more the converter is good and you have an o2 sensor going bad.

 

is that the first o2 sensor or the second....because i have the same code...but im not sure which sensor i might need. The second sensor is way more expensive than the first one. Anyone know for sure??

 

Im getting the Denso universal which is $60 for both. im going to replace the one after the cat first. Should I replace both sensors at teh same time? or is one just fine.

And thanks for the throstat idea im going to try that out