modifry

The short version - Advance Auto Parts has a "generic" downstream O2 sensor that's only $69 and appears to work fine as of 300 miles of varied driving. That's about a 75% discount from the OEM sensor.

[edit] - Passed emissions testing in Atlanta, direct OBD connection to verify ECM data, not tailpipe test.

The details -
I've been running for over 10k miles with a bad downstream O2 sensor because the catalytic converter was bad* and there was no sense changing the sensor till I got a new CAT. Plus I wasn't up for emissions testing till January so why not put it off as long as possible, right?

I recently found a low-mileage used CAT so last week I started looking for O2 sensors to see if there were any options besides original equipment. The sensor from Honda has cost me either $279 or $251, I guess depending on whether the parts guy got any the night before.

I had a hard time finding any on-line or local parts stores that carry O2 sensors for the S2000, but Advance Auto Parts did have 3 sensors listed. They have both the upstream and downstream sensors for $288 each, and a "generic" downstream sensor for $69. All three are made by Bosch, who makes the original equipment sensors for the S2000.

So I took a chance and bought the generic sensor. The obvious difference is it does not have the factory connector, just bare wires. It looks almost identical to the original sensor and I measured the heater resistance at 15 ohms, pretty close to the 12-14 ohms specified in the Honda shop manual. This was important because I know the ECM will throw a CEL if the heater resistance is too far off, and from my experience it does so almost immediately after start-up. Also, if the heater does not heat the sensor properly, the ECM will generate a different CEL within a few minutes of starting a cold engine.

The generic sensor comes with a special waterproof high-temp in-line splice box that allows you to cut your original connector off and attach it to the new sensor wires. This is good, because the sensor wires are stainless steel and you can't solder them, and I wouldn't trust crimp connectors in that environment. The splice box is very well made and does not require tools to install, except of course wire cutters to cut and strip the wires on the original connector. The silly thing is even though both the OEM and generic sensor are made by Bosch, the wire colors are different.

The good news is it comes with a chart to help you determine which color wires mate with the sensor. Unfortunately the chart is also "generic", identifying various OEM sensors as "Type A", "Type B" etc. As it turns out, the OEM color codes are all different, and there is only one "Type" that matches the Honda colors of BLK, BLK, WHT, GRY, which takes the guesswork out of it.

I installed the generic sensor along with the new (used) catalytic converter last Friday. Since then I have driven almost 300 miles under various city and highway conditions, including some "spirited" driving that would roughly simulate a few minutes of track time. I have gotten NO CEL's during this time, so it looks like the generic sensor may be a good match. Later this week I'll go in for my emissions check and that will be the real test.

*My first sensor failed at 92k miles. The replacement failed 10 days later when the sensor tip was broken off, apparently by something moving around in the catalytic converter. That's why I say the converter was bad. When I replaced the converter, I discovered the front element was no longer attached to the converter housing. With a little jiggling, it could slide backward and crash into the O2 sensor. I imagine the sensor can only stand so much bashing before it breaks off.

slalom44

That is great news, Modifry. Thanks for posting. Those O2 sensors don't last forever, and it's nice to know that you don't have to take out financing on your new sensor.

Please let us know how your emissions test turns out!

Chiung

modifry

[QUOTE]Originally posted by hecash
For reasons that I'm too embarassed to explain, I've had to buy two repacement oxygen sensors for the rear (cat) and got them both on eBay.

I bought an NKT for Honda four-wire for $69 plus shipping and a Bosch for Honda four-wire for $79 plus shipping.

Road Rage

Modifry: great info.

I would imagine that since the secondary HO2S really is only there to "check" on the first one, your fix will last, and the primary HO2S will function as it should, so your emissions should be a piece of cake. Good Luck!

s2000guy

I am not sure exactly what you are trying to say but the purpose of the secondary sensor is the check to see if the catalytic convertor is working properly. The secondary will not affect emissions.

modifry

Just thought I'd add that it passed emissions testing in Atlanta, the kind with a direct OBD connection to verify ECM data, not a tailpipe test. This is after a total of 600+ miles on the new sensor. And this is a Comptech SC application.

Road Rage

[QUOTE]Originally posted by s2000guy