O2 Sensor replacement
 

Hi guys,
I am new to the forum. Just bought an 86 Carrera. At PPI, I was told that the O2 sensor was dead. Two (2) questions:
1- I see there is a specific tool available to replace the O2 sensor. Is it a must ?
2- After replacing the O2 sensor, is there anything special to do (some adjustment and/or programming/resetting of the Motronic ?
Thanks

the tool is just a socket with a cutout for the wire or a flare nut wrench in the correct size (all 02s on all cars are 22mm, I think). it is often hard to remove them with an open end wrench (you can round off edges) so the tool makes it easier as does PB blaster spray. any auto parts store has the tool for $10 or so.

I just replaced mine on my '83, which was a simple one wire unit that you cut and then splice and heatwrap. As long as you are cutting the wire, you can get a box end wrench on it, and no need for the tool. Not sure if yours is a 3-wire sensor, and if you can cut it so easily though.

Mine was pretty stubborn, but PB Blaster and about 10 mins of wait time and it broke loose with a box end wrench. --DDD

hmmm... funny, I just dd a cat by-pass and swapped the O2 from the old to the new and dont even know how I did it... must be SO easy it didnt register....IIRC it plugs in on the 86' and I swapped it on the floor, came out easy with standard wrench but I had a good angle on it too....

No adjustment needed, just get one and put it in. Much less expensive if you get one without a connector and splice it to your original connector. I've read that our cars only need the "one" wire unit vs. 3 wire. (spend 20 to 30 bucks max.) The two white wires are for a heater to speed getting to operating temp at start-up. I replaced mine this winter. Buy the special socket if you like to own tools or you can only access it with a socket. Since you'll toss the old one, cut the wires and use anything that fits. Just normal tightness on the new one.

+1. And use a little copper-based hi-temp anti-seize on the threads.

I just replaced the O2 on my 85 this last weekend. I bought the tool, and although it was ~$25, it was piece of mind that I didn't end up with a stripped O2 sensor...

When I got into the job, here's what I did find - the tool helped immensely, as it will receive a socket wrench or breaker bar for added leverage, AND, I didn't have to remove the heat sheild next to the catalytic converter, saving me from needing to remove 6 more bolts that were definately frozen from rust / heat, as the O2 tool raised the height of where you would put the wrench. Would not have been possible to get around the heat sheild with a box wrench, and would not have had the vertical flexibility of the U-joint in the breaker bar.

Also, the tool provided better grip than an open end wrench when re-installing the new one.

Could it be done without the tool? Absolutely. Was it much easier with the tool? Absolutely.

Also, as mentioned - get some PB Blaster or CRC penetrant - give it a turn, back it off a little, then spray, wait 10 mins. Go a little more till it sticks, back it off, spray, repeat.

I also bought the three wire, so that I had an exact OEM replacement, which fit as intended without having to go to the additional steps of splicing wires, or looking at wiring diagrams any more than I had to.

One more note - when I bought my O2 sensor from pelican, there was an O2 relay for $12. I bought it too....but....for the life of me, and also for others I saw who posted they bought it too, could not find where it goes, and there was no mention of it in the Bentley book (reference chart on relays in the back) or the Chilton manual. The only place I saw MIGHT be a match was under the driver's seat, but could not confirm with the repair manuals that this was one and the same relay.

Interestingly as well, the part I ordered was not the same part number that showed up - I received the standard 'Bosch relay' vs. the part number stated on the order slip... that mystery aside, after replacing the O2sensor, it idled better, ran more smoothly.

So, anyone want to buy a standard Bosch relay, or have any additional thoughts on the O2 relay subject?

Having done mine and read lots of threads here, I really believe you can get an O2 sensor anywhere and they're all the same performance wise. Appear to be somewhat industry standard. My opinion, get one cheap at your area parts store and splice it in using your current connector. Lots of threads say the 3 wire version is overkill for out cars. A one wire version is less than $20 from Bosch. Get a 3 wire for $25 or $30, its a simple device.

if 84-89, you can use a 1996 Ford Taurus O2S and solder/splice the 3 wires.

Just use a 22MM box wrench. If you are anal about torque settings get the tool and torque to spec.

Put the new O2S on the cat 1st then connect to receiving end, if not you will twist up the wires.

It is the CHTS that you really want the proper tool/torque. Made my own.

Porsche O2 sensor........
 

When unplugging the factory connector from the wiring harness, be gentle with it. The end on the wiring harness has a tendency to break up or crumble if abused. I wound up using some epoxy to rebuild the body on mine so that it would still fit the connector properly.

One note if you are attempting to torque the O2 sensor using the available tool - it is a crow's foot configuration (i.e. the socket wrench hole is offset), so, It will not show an accurate torque reading, as you are adding length to the torque wrench from the fulcrum. You can over-torque. That said, I just subjectively tightened it to an "appropriate" Goldie-Locks tightness...not to loose, not too tight.

i recently replaced the o2 sensor on my 87 with a 3 wire. 2 white wires and a black. i had to splice the wires to put the factory plug on it.
of the 2 white wires, does it matter which one goes where as long as it's whites on whites and the black on black?

No. White on white, black on black.