O2 & Knock Sensor Issues

I'm working on a 96 Civic EX with a D16Y8 VTEC that keeps giving an O2 & Knock Sensor code. The Haynes manual says the Knock sensor is "threaded into a coolant passage" around the intake manifold. Seems like there are a lot of sensors in that area. Can anyone post a picture or describe a little more clearly where the sensor is?

As for testing, I have a great diagram for testing the O2 sensor with an ohmmeter. Does anyone have data for what slots on the connector harness to put the pins for testing the knock sensor?

There's a bunch of Temp sensors, which are used for guage, ecu, egr, and fan.
Disconnect a sensor while running, and see what fails.

The upstream O2 sensor is used for the air/fuel mix, buy a new sensor, and use the old upstream sensor down stream of the cat.

knock sensors do tend to break.. its directly under the intake manifold , center, 1 wire. red/blue stripe

Thanks guys. I knew about the two O2 sensors and their function. I just needed the location of the knock sensor. I'll look in the area described this weekend. As for testing the sensors, I had it backwards...I have a diagram for the harness of the knock sensor but not the O2 sensor. Here's the knock:
http://img.photobucket.com/albums/v473/CivicSpoon/knocksensor.jpg . I need some clear instructions for testing the O2 like these. Anyone have any?

I found a good video on ''How to Test a H02 sensor''
www.youtube.com/watch?v=1mb4VmDd0ao (http://www.youtube.com/watch?v=1mb4VmDd0ao)

I found a good video on ''How to Test a H02 sensor''
www.youtube.com/watch?v=1mb4VmDd0ao (http://www.youtube.com/watch?v=1mb4VmDd0ao)

Thanks bro. I don't have a gauge for monitoring fuel/air mixture, but I did find this at Youtube: http://www.youtube.com/watch?v=vdn4Dk5PSwc# . I noticed the O2 sensor before the cat converter was pretty black with deposits. The video suggests that indicated a high rich mixture. It looks like I need to set my voltmeter to the lowest voltage setting, connect the red probe to the black wire on the sensor harness & the black probe to the sensor body for a ground. I have the proper readings in my Haynes manual. I'm looking forward to this easy test. I'll post back with pictures and a report when I get to it this weekend.

Ok, I just finished adding a K&N air & oil filter, royal purple full syn 10w30 and a new fuel filter after a sea foam treatment to the oil and fuel systems. I did a radiator drain as I didn't have time to do a full flush due to the location of the thermostat. It turns out that the O2 sensor test isn't so easy. Problem #1: I'm not sure how to set my voltmeter up. It has a lot of settings. I need to research that some more. Problem #2: The videos on Youtube say to test the black wire as the signal wire, but there are two black wires. The Haynes manual says to test the white or red wire (white in my case) and to also test the heater wire but doesn't specify which one is the heater wire. The wiring schematics aren't very helpful either since it doesn't show which wire is what. Problem with the knock sensor is that it is buried under the intake manifold. I can't see it from above or below the car. I guess I'll have to remove the manifold? Any help with setting up a voltmeter, what wires are what on the O2 sensor, and how to get at the knock sensor would be appreciated.

Good news. After much searching the internet I figured out how to test my O2 sensor.

1. With engine off, insert a pin into the connected O2 harness, or disconnect and place the red probe on the white wire pin of the O2 sensor/or pin you just inserted.
2. Place the black probe on a good body ground.
3. Make sure the meter is set on 200m DC V.
3. Start the car. Meter should read 0.1-0.3 untill engine warms up (aprox 2 min)
4. After engine is at operating temp, the reading will jump anywhere from 0.1-0.9. This is normal and good.

My mil was on with a P0135 (Heater malfunction sensor #1). After I verified that the sensor was working properly, I tried to check the heater wire for voltage. Here is what I did (expecting a 10-40 ohms??? per Haynes):

1. Disconnected the O2 sensor harness.
2. With the meter set to 200 ohms (lowest I have) I;
Connected the meter between black & black/white = infinity
Connected the meter between black & black/yellow = infinity
This made me think that maybe Haynes meant 10-40 milivolts? since ohms tests resistance not voltage? So I repeated the process with my meter set on DC V 200. Both set ups read 0? Knowing that the sensor is working I decided to look at things from the PCM end. I found 1 black wire that had been spliced but looked to be a good connection. I re-taped it and put everything back together. When I read my OBDII codes all that I have is the knock sensor! That's great but I don't know why the O2 code went away.

To sum this up, does anyone see what I might have been doing wrong when trying to test the O2 sensor heater wire?

Thanks

I see many views but get very little input. Maybe were all here at AF trying to figure things out? Anyhow, I have my knock sensor issue corrected. I had to take the IM off which was a super pain. The manifold itself wasn't difficult; it was the old cardboard gasket that had become hard as a rock and stuck to the block. It took me 2.5 hrs of scraping with a razor to remove the thing! Once I got down below the IM, I found all kinds of loose wiring, wire hangers, harnesses, etc. Someone had been in there before and left it a mess! The biggest give away was the old knock sensor itself. Half of it was in the block and half hanging from the wiring harness! Someone had tried to silicone the thing back together! That was an easy $120 added to this fix. Buttoned it all up and no check engine lights. Only thing is, now I have other issues, but I'll start new threads for those.