O2 Sensors for a 99 996

[dbookman]

Can anyone offer recommendations on sources for O2 sensors for a 99 996, and also the procedure on how to replace them? My dealer is telling me it will cost $960 and about 4 hours of labor for this job, and that sounds completely outrageous to me. Are they easily accessible from below for a backyard hack mechanic? And do you recommend I buy the sensors from Porsche? Any recommendations, as well as a copy of the replacement procedure would be most helpful. Thanks!

[Loren]

I think OxygenSensors.com has OEM sensors. They are about $100 each there.

If you don't have a large (19 mm I think) open end/box combo wrench then you might want to buy one of the special slotted sockets they sell too.

There are 4 O2 sensors. Two on each cat. One before the cat and one after.

Are they suggesting you replace all 4? That seems very odd since even with sensor aging it is usually only one or two that need replacing.

Here are some general precautions with O2 sensors:

Oxygen sensor can be damaged if handled improperly.

    * Do not remove the plastic cap on the thread until just prior to fitting the oxygen sensor. The thread grease must under no circumstances come into contact with the plug.

    * Protect sensors - before and after fitting - against mechanical shocks.

    * Sensors that were dropped on the floor must not be used owing to the risk of a broken ceramic insulator.

    * The cables must not be twisted or kinked when the sensors are screwed in. Avoid pulling on the cable and plug.

    * Cleanliness in the housing of the plug connections is of utmost importance for the function of the oxygen sensor. Particles of dirt can impair the function of the oxygen sensor. There fore, the plug must be protected against any and all types of soiling.

    * Sensors with soiled or damaged plug must no longer be used.

    * Protect the cables and plugs when transporting the exhaust system with the sensors already fitted.

    * High-pressure cleaning equipment must not be used in the area of the sensors and plug connections.

    * Contact and corrosion agents, e.g. Stabilant, must not be applied on the plug contacts of the oxygen sensors.

[dbookman]

I think OxygenSensors.com has OEM sensors. They are about $100 each there.

If you don't have a large (19 mm I think) open end/box combo wrench then you might want to buy one of the special slotted sockets they sell too.

There are 4 O2 sensors. Two on each cat. One before the cat and one after.

Are they suggesting you replace all 4? That seems very odd since even with sensor aging it is usually only one or two that need replacing.

Here are some general precautions with O2 sensors:

Oxygen sensor can be damaged if handled improperly.

    * Do not remove the plastic cap on the thread until just prior to fitting the oxygen sensor. The thread grease must under no circumstances come into contact with the plug.

    * Protect sensors - before and after fitting - against mechanical shocks.

    * Sensors that were dropped on the floor must not be used owing to the risk of a broken ceramic insulator.

    * The cables must not be twisted or kinked when the sensors are screwed in. Avoid pulling on the cable and plug.

    * Cleanliness in the housing of the plug connections is of utmost importance for the function of the oxygen sensor. Particles of dirt can impair the function of the oxygen sensor. There fore, the plug must be protected against any and all types of soiling.

    * Sensors with soiled or damaged plug must no longer be used.

    * Protect the cables and plugs when transporting the exhaust system with the sensors already fitted.

    * High-pressure cleaning equipment must not be used in the area of the sensors and plug connections.

    * Contact and corrosion agents, e.g. Stabilant, must not be applied on the plug contacts of the oxygen sensors.

<{POST_SNAPBACK}>

[dbookman]

That's for 2. Their diagnosis was based on my OBDII computer registering 1123, 1125 and 1300 faults (taken with my own code reader). So it sounds like the O2 sensors should be fairly easy to access and replace, just as they are with just about any car?

[1999Porsche911]

There are many places on the net to get the Bosch sensors for around $100 each as Loren said. It will take you maybe 1 1/2 hours to replace all 4, but like Loren asks, why in the world are you replacing all 4?????? Hook up your scanner and take a look at each sensor. Do not have a good scanner??? Take $250 from the money you were going to give the dealer to do all this unnecessary work and buy one.

Edited August 4, 2005 by 1999Porsche911

[1999Porsche911]

I think OxygenSensors.com has OEM sensors. They are about $100 each there.

If you don't have a large (19 mm I think) open end/box combo wrench then you might want to buy one of the special slotted sockets they sell too.

There are 4 O2 sensors. Two on each cat. One before the cat and one after.

Are they suggesting you replace all 4? That seems very odd since even with sensor aging it is usually only one or two that need replacing.

Here are some general precautions with O2 sensors:

Oxygen sensor can be damaged if handled improperly.

    * Do not remove the plastic cap on the thread until just prior to fitting the oxygen sensor. The thread grease must under no circumstances come into contact with the plug.

    * Protect sensors - before and after fitting - against mechanical shocks.

    * Sensors that were dropped on the floor must not be used owing to the risk of a broken ceramic insulator.

    * The cables must not be twisted or kinked when the sensors are screwed in. Avoid pulling on the cable and plug.

    * Cleanliness in the housing of the plug connections is of utmost importance for the function of the oxygen sensor. Particles of dirt can impair the function of the oxygen sensor. There fore, the plug must be protected against any and all types of soiling.

    * Sensors with soiled or damaged plug must no longer be used.

    * Protect the cables and plugs when transporting the exhaust system with the sensors already fitted.

    * High-pressure cleaning equipment must not be used in the area of the sensors and plug connections.

    * Contact and corrosion agents, e.g. Stabilant, must not be applied on the plug contacts of the oxygen sensors.

<{POST_SNAPBACK}>

<{POST_SNAPBACK}>

Get a scanner...not a code reader. Extremely unlikely that both 02 sensors are bad. You are running rich. Clean the MAF.

http://www2.autopartsauthority.com/parts/a...or&category=All

Edited August 4, 2005 by 1999Porsche911

[dbookman]

Thanks. I should have mentioned that I already cleaned the MAF and replaced the fuel filter. With 37K mi on the car, I'm wondering if I need O2 sensors at all.

Edited August 4, 2005 by dbookman

[Loren]

Correct, those codes do not indicate you have a bad O2 sensor. As 1999Porsche911 said you are running too rich. If you have cleaned the MAF and are sure it is okay then check the EVAP canister for leaks, or cracks or an open purge valve.