1996 civic ex coupe 145K miles. im looking to replace my o2 sensors. honda automotiveparts.com lists two different number for the sensors. ngk's website lists the same for the upstream and downstream. any suggestions? im sure i cant send them back if theyve been installed.

 

i would call the Honda dealership, and ask them if they are the same part #.

 

Why do you want to replace them? The one downstream does nothing but report the health of the cat. If you have no check engine light for an inefficient cat there is no need to replace. The one upstream is the one the ECU uses to monitor your air fuel mixture and unless you are getting bad gas mileage (and have tried the usual tune-up stuff) I doubt the O2 sensor is going bad. I have a 97 and failed emissions with an aftermarket O2 sensor. I re-installed the original O2 sensor that had 160K miles on it and it passed emissions without a problem. Unless you are absolutely sure the O2 sensor(s) are bad, I wouldn't replace them with anything aftermarket.