I've had my Civic hatchback (99) for a year now and I've had troubles with the O2 sensor a few times already. The first time just a day after buying the car, the check engine light came on for some troubles with the O2 sensor and I ended up changing the catalytic converter. Then last spring the same thing happened and this time I changed the O2 sensor itself.
Last week the light came back on and no surprise, it's still P0131, trouble with the O2 sensor (low voltage). It seems clear that I have an emission problem but somehow I doubt that my O2 sensor is the problem itself.

Does this happen to some of you? Would anyone have a suggestion on what I should be doing?

thanks!

 

Your Civic has two O2 sensors, one before the catalytic converter (primary sensor) and one after the catalytic converter (secondary sensor).



P0131 indicates a problem with the primary O2 sensor, the ECU, or the fuel pressure. Therefore, you may have replaced an expensive catalytic converter unnecessarily. Did you replace the primary or secondary O2 sensor? If you replaced the primary O2 sensor, then I'd suggest that you next measure the fuel pressure: