I have a 1997 Honda Civic DX. The "Check Engine" light is on. There are two O2 sensors, one on the top before the converter and one on the bottom which is after the converter. Is there one sensor that tends to go bad than the other? I wanted to see if I could just replace one and not both to save some $ instead of buying both right away.
Also, has any one had any luck with aftermarket O2 sensors? I noticed that they sell them on line but they were universal and did not have the same plug on the end, just bare wires and I assume I would have to use the connector from the old sensor.
David

 

The ECU code will tell which sensor to replace. You can buy aftermarket sensors with a plug already attached and guaranteed compatibility at auto parts stores. I wouldn't mess with ebay for such a small dollar difference. Actually check the dealer's price on the sensor because it may not be that unreasonable.

 

My civic has the same warning light (33k miles). Took it to dealer. dealer said it was computer malfuction, reset it, now fine. For things associated with computer, you might better off by taking it to a dealer. paid either $35 or $50 for labor.

 

Don't just assume it is an O2 sensor. That light could mean 20 differnet things. You could have something else wrong or something that needs adjusting.

At least have the code retrieved by someone who knows what they mean so you have an idea what area to start checking.

 

OK thanks. I have a 1996 honda civic also and I checked with the parts dept at honda and the 96 and 97 civic use the same part number O2 sensors for both years. So just for grins I installed the O2 sensors from the 96 civic into the 97. I reset the computer by disconnecting the + and - cables from the battery and held them together to reset the computer or clear the codes. So if after a few hundred mile it stays out I will replace the sensors, if the light comes back on again I will take the car to the Honda dealer and see if they can tell me what else is wrong. The last time I cleared the check engine light codes the light came back on after about 90 miles.
Thanks for the help!!!!

 

when you have a check engine light, take it to a parts place or the dealer to check the codes, then go from there. and the 1st o2 sensor seems to go out more often than the rest from what i've heard, seen, and experienced.

 

huh, I'd heard that the downstream sensor throwing a code occasionally (and actually going out more often than the upstream one) was pretty common in hondas. It could mean the sensor is bad if it happens a lot of course, or it could mean there is something wrong with your cat (blockage or worn out), supposedly even a clogged air filter can causethe downstream o2 sensor to throw a code. I just went through this with thehead honcho down atNapa the other day.

I ended up just doin an oil/oil filter/air filter change and no code since. (Only been a few days tho, but the check engine light had previously been onconstantly for a long time)

Also according to the guy at Napa (git yer grain'o'salt ready, I don't know this for sure) the downstream o2 sensor doesn't affect ANY other engine systems. It's just a fail safe for emissions standards, if it throws a code it means you MIGHT fail emissions if tested, orthe sensor isbad...

A confirmation or correction about this would be greatly appriciated! TIA

 

the downstream o2 sensor senses if the cat is working properly, and if all of the gas has been thoroughly burned, if it hasn't, it sends a code to the ecu to compensate the fuel input.

and as for the 1st o2 sensor being the first to burn out, i only meant that for nonvtec d16's and it's exhaust setup.

 

I wasn't saying I thought you were wrong, just fact checking what people had told me...

Thanks for the info!

 

THIS is true... but is the PRIMARY (upstream) sensor that checks the air/fuel ratio, not the secondary