O2 sensor - What is the correct wire coloring?

[Vanguard]

I got a Bosch universal. Their installation instructions at http://www.boschusa.com/images/OxygenSensorInstall.pdf has a table showing color codes so you can supposedly match up the colors for the connector (the old one you reuse) and their wires on the replacement O2 sensor.

 

The Bosch had 2 white wires (for heater) and 1 black wire (for sensor). My old connector (for my Subaru '92 Legacy L AWD non-turbo) had 1 white, 1 red, and 1 black. Well, there really is no match in their table other than noticing that the only red wire listed in in the heater column. My old Subaru 3-pin connector had the following wire colors:

 

white

red

black

 

The Bosch had:

 

white (2)

black

 

So I hooked them up as follows:

 

Subaru white -> Bosch white

Subaru red -> Bosch other white

Subaru black -> Bosch black

 

Does that sound like the correct hookup? I ask because after replacing the oxygen sensor, the CEL (check engine light) is still on. I disconnected the positive cable from the batter for over half an hour which, as I read, should've reset the computer. But when I started the car, and after driving it awhile, the CEL still comes on. So either I didn't connect the O2 wires correctly, or it is one of the other possible components that are bad (purge valve or knock sensor). The error codes showed 3 codes (O2, knock, and purge valve) so I figured the O2 might've been most likely the culprit. Maybe not, or maybe I didn't wire it correctly.

 

Before installing the O2 sensor, I did check resistances but only remember one of them right now. Between the red and white wires, the digital ohmmeter showed a resistance of 1500 ohms. Presumably the heater is a wire coil with resistance that heats up when current goes through it. However, I do recall the continuity test showing the black and one of the other wires were connected. Should the black (sensor) wire show connectivity at any ohms to the other leads?

[nipper]

Look at my post "get it while its hot" it should have the wiring diagram there (i think)

http://www.ultimatesubaru.org/forum/showthread.php?t=43489

 

nipper

[Vanguard]

Thanks, nipper, but it didn't list the color code for the wires for the O2 sensor. Although not the same place as before (which were a copy of install instructions that shows the shape and wire colors for LOTS of car brands rather than Bosch's very incomplete table), I did find a color code at:

 

http://www.sparkplugs.com/sparkplug411.asp?kw=NTK+Universal+Oxygen+Sensor+Installation+Instructions&mfid=0

 

So it looks like I guessed correctly. I connected the red and white wires from the old connector to the white wires on the new universal O2 sensor (for the heater) and the black wires together (sensor). However, and although the computer was reset (by disconnecting the battery for half an hour), the CEL (check engine light) is still on. Oh, well, onto trying the next part.

 

When I read the error codes using the flashing CEL method, the O2 sensor, knock sensor, and purge valve (which I assume means the canister purge valve) were all listed when using the black test connector. So either the wiring job wasn't satisfactory (Bosch gave me "posi-lok" connections that rely on a friction fit to jam the wire against a metal stud in the ferrule), or the O2 sensor wasn't the problem, or I actually do have more than one cause as shown by the error codes.

 

I figured the O2 sensor was the most likely candidate. The old one was coated white on the tip (a bit of carbon black at the base). The only image that I've found (from Bosch) is that a white coating means fuel contamination but that's not very specific, like too much alcohol (here in Minnesota it is mandated that ethanol be mixed with gasoline), coolant, additives, or whatever. So I'll have to read the codes again and hopefully the O2 sensor won't be listed anymore.

 

Now, of the remaining error codes that were read before, I get to guess as to which is most likely candidate to replace first: knock sensor ($66) or purge valve ($85). I just got nailed for $600 to replace the calipers, pads, and rotors on both sides on the rear axle. Ouch. Guess there's no getting ahead of the curve.