It is the orginal one on car at 230k miles
No check engine light is on so i don't know if it is bad or not...

 

Is your CEL on? I think they're generally good for about 100k. Have you pulled them to look at them?

 

no check engine light is on

 

*facepalm* Yeah, I should have read that one more closely. Sorry.

As far as I know, if one of your O2 sensors had failed, it would have tripped the CEL. I'm not aware of any exceptions.

 

Question #1
What makes you think the O2 sensor is bad if you don't have a CEL.

Statement #1
And O2 sensor most likely will trip a code yes, but rare occasion it may not.
My car (1995 honda accord ex ... OBD1) did not trip a code, but when I tested it, It was fried.

My opinion, After an O2 sensor has seen 230k miles it'd be best to get a new one even if it is working right, its probably not working to its fullest capability.

 

I've found these things rarely throw a code. But if you're certain it's original you should without a doubt replace it. It's like 40 bucks from rockauto..be sure to search for a rockauto code. I've had 4 4th gen accords and I've replaced all the oxygen sensors upon purchase and the spark plugs are always carbon fouled from the gas running rich on 'em when I have changed out the spark plugs when I did the first tuneup.