Oxygen Sensor - Where does it plug in?

[Emission]

I know where it is on the exhaust pipe... but the three covered wires run into the engine bay and disappear! Where is the other end?

(I am hooking up a simple fuel/air meter - it reads the sensor for data - and I need to tap into the wire. I am trying to see where the other end terminates.)

Thanks.

[dickster]

if you look inside the engine bay on the left, it should go to a connector halfway along the chasis member opposite the centre spark plug!! the connector is maybe 1 1/2" - 2"long

around that area anway!! good luck.

[beepbeep]

Make sure you have high-impedance input in your A/F meter! Voltage output from sensor has very low current and you might bring it down by just connecting your meter in parallel.

Also, you don't need to tap into all three wires, there is only one that is sensor output.

[Emission]

I understand there are two white and one black wire.

The two white are for heating the unit, while the black wire is the sending wire.

Thanks for the replies.

[PDACPA]

Does the oxygen sensor disconnect from the wires so that you can replace it or do you need to feed new wires on the new unit? Doing the pre-muffler install, I was going to replace my O2 sensor.

Anyone have pictures?

Thanks

Wayne's book is at home and reading this post got me wondering

[dickster]

my non oe one came without the plug so i soldered the wire together. not sure about oe.

[targa80]

I tapped a wire into the lambda box under the passenger seat to use a dwell meter to monitor the O2 sensor voltage. The signal is the one coming from the O2 sensor. This is on a 80SC so I don't know if the 86 has the lambda control box under the passenger seat.

[PDACPA]

My 89 has 84k miles. I have never changed the O2 sensor but from reading here it sounds like I should.

Is there any reason to? Do they go bad?

I am going to be doing the premuffler so figured if i am there might as well, but that little thing is $125.


Also, when you swap it out, do you have to rewire into the engine compartment? IS this easily done? Thanks

[scottb]

Installing and wiring the O2 sensor is very easy. Some people use generic sensors, and cut off the harness and rewire it with the harness from the old sensor. It's an easy job, and the generic sensors are substantially less expensive. There are mixed opinions on whether to do this, however. Do a search on the board. There was a long thread about a year ago (maybe less) which discussed the merits (or lack of same) of using a generic sensor versus a Porsche-specific sensor.

Good luck!

[PDACPA]

Scott

If I buy the regular O2 (the one our host sells I assume is the regular and not a generic) is there any rewiring or its just plug and play?

The wires do not look that long in Pelican's picture but someone mentioned about it going thru the car I thought.

Will search for that thread.

Thanks

[kepperly]

I just purchased a new Bursch "test" pipe (here in Kansas we can test all year) the o2 sensor is just plug and play. replace all the bolts with stainless and buy all the gaskets. We had to Burn off the old bolts on the cat and with our local aircraft surplus sales only selling sae stainless, had to drill out the flanges for 1/2 bolts.
To replace the cat on a 3.2 it requires three differant gaskets,
one is 27.00, one is 10.00 and the muffler gasket is only 3.00 from our host. All came in Porsche part # bags.

Keith

[dickster]

Is there any reason to? Do they go bad?

yes, they should be changed as part of routine maintenance on 60k (i believe its 60 from memory).

$125 isn't bad for 60k

[PDACPA]

Dickster

I have about 87 k on mine and as far as I know, no one has changed it. Guess its time. I am going in, might as well do it!

[zzwhm]

My local porsche parts guy recommended a Bosch universal O2 sensor for $45. Clip the wires and splice it into your current harness - solder the connection and use heat-shrink wire wrap to seal/protect. Other than needing a new wiring harness is there a reason to go the more expensive route?

[scottb]

PDACPA: If you're getting the OE sensor from our host, it's plug and play. Intallation is very simple...there's a shield that clips to the sensor. I removed that, and I think I removed another shield that bolted to the catalytic converter (though not sure about this). The sensor came out easily, and the wire removal was a snap. Don't forget to use a bit of anti-sieze on the sensor threads when you put the new one in....but don't get any on the "business end" of the sensor.

Good luck.

[barlowdo]

Why not disconnect the connector and test the O2 before replacing it ? I thought I read in 101 how to test it.

I think 2 volts tells computer to run lean and 0 volts tells it to richen the mixture but don't quote me.

I believe you just put a voltmeter on the lead coming from the O2.

But I am not sure which of the three leads is the O2 as the other two are for heating. From above post it sounds like it is the black wire. I am guessing you need to ground the voltmeter to chassis to get continuity.

-Don

[scottb]

There are three wires on the sensor. Two are of the same color (i.e., two are white, or two are black). The two that are the same color power the heating circuit. The single other color wire handles the sensor circuit.

I bought the universal sensor and, as ZZWHM said, simply soldered the wires and put heat shrink over the individual wires and then over the entire bundle. So far so good!

[PDACPA]

Thanks Scott. I am getting my order ready to buy from our Host. Glad to hear that I can replace it with no soldering. That was my concern as I have never really done any soldering (yet).