I was just trying to test the O2 Sensor on my 1990 Honda Civic and I wanted to see the difference between it connected and disconnected while driving...So I turned on the car and let it heat up for like 15mins, then disconnected the O2 Sensor plug and noticed nothing happened noticeably...So then I went for like a 20 minute drive...Car ran fine, no hiccups nothing...What I thought was odd though was that the check engine light NEVER came on the whole time driving or even idling...I even checked for a code on the ECU after and there was nothing...Is something wrong here?

DJ

 

When my turbo blew a seal, I put my DC Sports header back on. The O2 sensor was in the bottom of the back of the header. I couldn't find the extension that the header came with for the O2 wire so I ran it with out it for a week (I needed to get to work) while I ordered a new O2 wire extension. I never had a problem running it with out the sensor pluged in.

 

Yeah mine seemed to run fine, but did you get a check engine light or a ECU code come up?

 

The check engine light would come on and go out. I didn't seem like it affected the performance of the engine while it was disconnected.

 

YUP my 90 civic hb si is the same too. the O2 sensor has been out for like a year. I don't really mind because it's in storage. But when i drive it for about 5 minutes the CEL will come on. It only comes back on when the engine is warmed up.

I don't think it's hurting performance in any way. it probably runs even richer... which is good for above 5,500rpms

 

takes a few days for cel to go on depends on the car