Hi I just had my o2 sensor replaced and did it myself. My problem is that I thought my o2 sensor was bad because when we took out the old o2 sensor out, we had to use a cutting torch to do it. We just heated up the surrounding so we can turn the old o2 sensor(stuck!). I had to remove because I was replacing my flex pipe.
After I installed the new flex pipe. I reconnected the old 02 sensor, when I turned the engine on, CEL came on. So drove it and the CEL came off but after awhile came on again. so back on the ramp and check the o2 sensor if connected properly and it was ok.
I drove it to work for 2 days. I notice that my gas milage went bad, so I said I am buying a new sensor now, now I bought a new o2 sensor because I was thinking the old one is already bad, I drove the car on the ramp and replace it. CEL was still on when I turned the engine on. I check the other sensor and found out that it was completely disconnected. I connected it back and mde sure it was connected. Drove the car, CEL is still on. Help

My car is a 2001 Accord LX 4cyl.

 

Did you disconnect the battery before you unplugged the o2 sensor? and while you installed the new one? also make sure you dont touch the end of the sensor because that will also mess up the sensor.

 

thanks for the reply, no I did not disconnect the battery when I unplug it and when I installed the new o2. I did not know that I had to disconnect.

 

Reset the ECU and see what happens

 

thanks for the reply co-owners. I was driving the car tonight on the way home. I did bring the rpm to 6100 on 1st and 2nd gear. After that the CEL went away, I was very happy that it finally went away. I was worried for a while.