About 3-4 years ago my 1999 Integra GS-R started to hesitate/surge while driving. While the accelerator was pressed down, the motor would lose power for a second or two and then it would jerk and regain it. After taking it to the dealer, they found out it was my O2 sensor that was bad so they replaced it.

My car has been fine for years, but a few weeks ago my car started showing the same symptoms again. Could it be the same O2 sensor going bad again or do you think its the second O2 going bad?

I have a CEL/MIL on with a P0420 code, but i've had this code forever. I just changed my CAT to a carsound/magnaflow exactly 1 year ago so I don't know if this code has anything to do with O2 sensors. Any help would be appreciated. Thanks in advanced.

 

you have to see what the after cat sensor is reading or if its lazy. the higher flow cat may be throwing off your o2 sensor

 

How do I see what the after-cat sensor is reading? By the way, the sensor the dealer changed a few years back was the before-cat sensor. At 116k, I think my after-cat sensor is now failing.