I have a 1990 honda civic 1.5. Recently the check engine light has been going on and then the car runs very poorly, I think in limp mode. If I shut it off and restart the light goes off and it runs good again for a while till it goes on again Fault code show 1 (oxygen content). I replaced O2 sensor. Checked wiring. NOW WHAT?

Make sure you installed an OEM or Denso oxygen sensor--other generic sensors (such as Bosch) won't work.

Hi Thanks for responding. I replaced it with a Denso, but I had to attach the old connector, since the one that it came with did not fit the connector on the car. But now what would be the next thing to try? I have continuity between the sensor and the computer, and now I don't know what else would cause this fault code. Could the computer be bad?

Your problem is with the connection. You cannot cut, splice, or mess with the pigtail or connector on the oxygen sensor. Even getting WD-40 on the pigtail will knock the sensor out--they are extremely sensitive. I would buy a new OEM oxygen sensor that fits perfectly. Take the connector that fits with you to get an exact match.