JGriff

I was looking through the receipts that the PO gave me on my recently-acquired 1990 S2, and I didn’t see a receipt indicating that the O2 sensor has ever been replaced.

The car currently has 75k miles on it. What is the change interval for O2 sensors on these cars? Most cars are at about 60k miles. Should I consider changing mine soon? How many are there on an S2? One or two?

Are these easy to replace? I’ve done the two on my ’92 Audi 100S, so I’m not a stranger to changing them on cars that I own (i.e. I have the O2 sensor socket to remove them). I’m just wondering how difficult a job it is to replace it/them on an S2.

Are there any websites with pics and/or an explanation of the replacement process?

Thanks.

Jim

newoldguy

They aren't very expensive if you get the "universal" replacement. I would think you should do it if you have reason to believe you are on the original one. I don't know about your engine but on my '87 n/a it was easy to do in the driveway on ramps. Just had to get it out (sprayed first with PB Blaster), disconnect at the engine bay end, take to bench and cut connector off old one and re-connect to new. Screw in first, then re-connect up top. Pretty easy overall in my opinion and certainly within your capability if you've done them before. Have fun!

Oh, there should be old discussions on this topic in the search function to read some more on it.

Adrian

I do not recommend you purchase the "generic" version of the O2 sensor. You can get into a lot of trouble with these and water. If you drive in the dry and when the sun is shining only, then they are okay however if you are in the wet they can cause you horrible problems. You will find articles on this subject in archives.
The extra dollars are well spent purchasing the Porsche version.
They normally last around 100K of your miles. They are not hard to change but make sure you get it well lubricated to remove it first. Liberal use of a good penetrant. If you do not do this you can strip the thread out of the cat,
Ciao,
Adrian
911C4

JGriff

Thanks for the prompt replies. By the sound of it, there is only one on these cars… that’s good. My ’92 Audi 100S has two of them… hence twice the cost and twice the time to do the job!!

With regard to OEM vs. generic, I too am an advocate of the OEM unit. I had to make the decision when doing my Audi (at twice the OEM cost… Ouch!!), and I chose to buy the OEM unit with the factory connector. My reasoning was this:

1. It was designed this way i.e. not a spliced connection.
2. Easier to replace.. i.e. no soldering of connections
3. Don’t have to worry about the soldered connection coming loose or corroded.
4. If the car starts to run weird or sluggish or gives a check engine light, I want to feel confident that it is NOT the O2 sensor (and its soldered connection). It would be one less item to check.
5. Even though it cost a lot more than the generic, it is relatively small $ for peace of mind, given that it only needs to be replaced every 60k or 75k (or 100k) miles. (Analogies: To save $$, putting on retreaded tires, gluing new brake pad material onto worn backing plates: both are not worth the time or the sacrifice in performance and safety.)

Just my $.05 worth.

Again, thanks for the responses.

Jim

John Anderson

Actually Adrian is correct/incorrect.

YOu can stop by any pep boys and buy a BOSCH O2. THey carry about 50 different BOSCH sensors, each has a different plug and thus, the price difference that varies soo much, the Porsche claims a huge price tag, when the same sensor for another "daily driver, non performance" car with a different plug will cost only forty bucks. A BOSCH three wire is a BOSCH three wire, cut the old plug from yours, by the forty dollar replacemnt BOSCH sensor, solder your old clip to it and your on your way.

Adrian

Dear John,
One of our 964 colleagues did exactly this. Went to pep boys, paid somewhere between 40 and 60 of your dollars, soldered the original plug in, installed it and bobs your uncle off he went. Until it rained. Then the 964 would do all kinds of horrible things. Took him six months to trace the fault to this "Bosch O2 sensor". The different between the Porsche version and the Generic version was the position of the vent hole and the fact that the wiring was sealed at the top to stop water ingress.
Why is this important. the poor oold O2 sensor on a 964 gets drowned in the rain. A switch to the Porsche version and the problems are gone. You might think they are the same, they might look the same but sometimes (and only sometimes) there are subtle differences.
Buyer beware and if the O2 sensor is running in a Motronic DME system, ala 964 and up I strongly recommend you use the original. Also for a 1990 944 S2 as well.
Ciao,
Adrian
911C4

John Anderson

Adrian,

I have never heard of this, I have driven in the rain a few times :-) So has many, countless customers...never had the problem, but then again, we use the factory shield when we solder the wires, this protects it from the rain and heat. Maybe thats the difference? Maybe its the location oin the 951...its highre up the exhaust system, I'm not doubtling you, honestly, I'm just offering my experience. Maybe together we can find the fault here :-)

Take Care!

Adrian

Dear John,
Location of the O2 sensor plays a significant role. Porsche models are going to be different. Different exhaust systems are used around the world from the factory, and there are the aftermarket systems, bypass pipes etc. Too many variables really. The 951 also does not have a Motronic system so is less sensitive to such things. The purpose of my posts is not to say "Don´t" but to say "Beware". You could save 40 bucks today and spend hundreds tomorrow. Same applies to things like relay whilst we are at it. Same Bosch part number, different current ratings.
We will never find an answer to this but as long as people are aware of "Potential Problems".
Ciao,
Adrian
911C4

John Anderson

Hi Adrian!

The 951 Does use Motronics and a KLR. YOur right, placemenmt must be an issue here.

Porscheclub

Hello everybody,

I got a same problem with my 944 N/A 1987.

BUT ANY WAY: To avoid any problem to replace any part of any Porsch or other car please use OEM parts or direct manufacture supplier parts for the Porsch or othe model.

I's help you avoid many problems and save thousand of dollars and many time will be not wasted.

I hope info below can help resolve all your OS2 problem and answer for the most your questions.

Thanks
Eugene.

Tools

• Appropriate Size Open End Wrench (most take a 15/16" or 24mm)
• Crimp Type Wire Connectors
• Wire Connectors
• http://www.clarks-garage.com/shop-manual/fuel-18.htm

General Installation Tips

If you are replacing the O2 Sensor with a universal replacement sensor, you'll have to splice the factory connector plug onto the new sensor. Or if you've order a sensor kit which comes with connectors, you'll have to install the connectors which come with the kit onto the new sensor wires. DO NOT solder the connectors onto the wires.

They must be crimped on for the O2 sensor to work correctly. For the sensor to work correctly, it must draw clean air down to the sensor through the air gaps in the stranded wire. If you solder the wires, the solder will fill the air gaps in the wire and the sensor will not work correctly.

Do not use any silicon based chemicals that could become exposed to the O2 sensor. Silicon will contaminate the sensor and it will quit working. Many RTV sealants, gasoline additives, and anti-seize compounds contain silicon so, check the label before you use it.

Replacement

1. First locate and disconnect the O2 connector plug. It will be a round connector plug at the back of the engine (unless it's been previously replaced with a universal sensor with plug kit). If necessary locate the sensor first and trace the wire up to the connector plug.

2. After you've unplugged the sensor, locate the sensor and remove it using the appropriate size open ended wrench (or O2 sensor socket if you happen to have one).
If you are installing a universal sensor, you can find detailed instructions for installing the universal sensor here. >>> http://www.clarks-garage.com/shop-ma...sorInstall.pdf
3. Install the new sensor and tighten.
4. Plug in the new sensor.

Clark's Garage © 1998

Ronin-951

Very Good 'Porscheclub', TOTALLY agree with you. Now we need to educate the masses on stock vs aftermarket spark plug wires next. Welcome Aboard.