EMC2

Last December I had a single CEL light come on and a Duranetric scan exposed a code 3104 "catalytic convertor, bank 2 inadequate effect, upper limit value exceeded".

I ran some tests with the car running and both left and right bank sensor graphs appeared to be tracking very similarly (I.e. within spec)

After speaking to the dealer and some friends it seemed best to monitor closely and see if the fault reoccurred.

After many trips at varying speeds over 6 months no more errors occurred until finally about a month back the same code showed itself on the same sensor and bank.

After a bit more research it was clear that these sensors can and do go bad. My car had over 70k miles at the time.

I ordered a replacement sensor:
Porsche 911 09-12 Oxygen Sensor Before Catalyst OEM BOSCH 9A1 606 168 02
Approx $120 shipped

I also bought an oxygen sensor socket to assist with the job.

The job is very easy (and a little more in my case because I don't have the side mufflers installed). With the side muffler out the way you have easy access to the sensor and access in the engine bay is very good also. No need to remove the airbox.

All you need to do is observe carefully the path that the cable follows and where the retaining clips are, to ensure the new sensor cable is properly secured.
The whole job including removing and replacing the rear wheel took about 45 min's as I did it slowly (first time). Could do this again in under 30 mins easily.

It's been about a month now since the swap and no more codes.

Excuse the pollen in the engine bay (pollen season seemed to last a lot longer than usual this year)

Cloudspin

Great write up. Thanks!

rherring

Thank you for posting this. Great DIY!

mreloc

Awesome pics and instructions. Thank you!

EMC2

No problem guys. Hope it helps someone in future

HenryPcar

Do you how many total sensors are there on a 997.2 ?

DC911S

there are four of them. Two on each side, one before the cat and one after.

HenryPcar

Great DIY info. However, my problem is how to undo the plastic plugs in the engine bay on the side ? I can't unplug it and I don't want to forcefully breaking it.

swingwing

Great write-up, thanks. Info request from me, Porsche newbie: What is the cylinder layout and bank definition for my '09 Carrera?

Turboslut

Is there any procedure or adaptation necessary to let the ECU "know" it now has brand new sensors in place?

RichBunch

Should be able to just clear codes.

jdubdds24

Ok So I just did this job, for anyone interested I thought Id share my experience. I have a 2009 911 C4S 6spd, PSE with sharkwerks crossover pipe. I have a softronic tune, dont get me started, i hate the tune, it doesnt do anything, and i feel like it partially to blame for the O2 sensor failing but i have no 'proof', and all in all it was a 100% waste of money.
At any rate, was driving it home from work when the dreaded CEL came on. I plugged in my durametric and it pulled a P0004 code...great, a generic code that tells me nothing. I have another OBII scanner that bluetooth connect to my phone, so i plug that in and go figure...it tells me the code, P0431. Catalyst 1 Efficiency Below Threshold Bank 2. Commence with research, Bank 1 is drivers side (for US based cars), Bank 2 is passenger side. So this tells me either my cat is bad or my O2 sensor is bad. There are two sensors and I cant remember why but something pointed me towards it being the downrange O2 sensor "post-cat". So i ordered one up. Got up under my car and saw an O2 sensor sitting right in front of my face and thought, "this is my lucky day". Well it was the wrong sensor, the one you can see is the precat sensor.

So, can you reach the downrange sensor with just removing the rear wheel? I guess anything is possible but it was not possible for me.
At this point I committed. Took about 10 min got all my tools set up and dove in. Took the rear bumper off, took the right rear heat shield off, took the muffler off, and took the inner smaller heat shield off. It was only with all these things removed that I could get my special O2 sensor socket on there to get it out. I unplugged the end from the right side of the airbox in the engine bay and traced it down so i knew the routing of the new one. It really isn't a hard job, I've taken all that stuff off before myself when I did spark plugs, then ignition coils, then again for when i put a new exhaust in. I should've just committed from the get go rather than dicking around with it for 30-45m because i was stubborn and didn't want to do "all that work". Once i was done i remembered it wasnt that bad.

Anyone know how much the dealer charges for an O2 sensor replacement? Curious. Hope that helps anyone looking at doing this in the future.
I also emailed the guy from Softronic and he was sure it was a catalytic converter failure and I was not convinced that it was. I'm swapping back my tune to stock. And now i have a $1000 OBDII dongle paperweight...

EDIT: forgot the most important part, i tried clearing the CEL codes from both my bluetooth OBDII and the durametric. You cannot cancel these codes. So went for a drive...and kept driving...still not going off...so i drove some more...i stop, pull over, turn the car off and on again...nope, still have a code...ugh...ok so i start driving home, about 15min out and BOOM the light turns off...hallelujah. About 30m of driving before the light turned off. NICE.

VT Blue

Which OBDII Bluetooth scanner did you use?

Thx!

Bob

jdubdds24

I have one called bluedriver. I think it was like $100 on amazon. Its not great but not terrible. I think there are probably better ones out there. I was a little surprised that it gave me the proper code over the durametric though.

Hornet_312

I have one sensor that trips every few months. Local dealer quoted $600, so I've held off. Will probably have them do it at some point, but hard to stomach seeing as the same repair on my F-150 would be $150.