Honda Civic 02 sensor

Which one did you break? There are more than one. Now if it is the bottom one and I say this based on a guess that you have a 4 cylinder, you might notice a small idle problem and a loss of fuel economy. The upper O2 may cause the idle to be worse, etc. I have driven with the lower disconnected for about a 1000 miles without any noticeable difference. I would imagine and hope that the check engine light is on.

That is the most critical one and I would get it replaced very soon. They are available at the local car parts store or online. Can't remember the website but the is one that just handles O2 sensors and they carry them all. They were quite reasonable. They have them on ebay.

Replace it. You car will thank you and the environment will thank you too!