Post Cat O2 Sensor Ageing Bank 1

[OscarAH1W]

Okay guys, I have been getting the CEL with this code for a while...  reset, drive a few times, no light... then returns on way home from Autocross...  So I order a post-cat O2 sensor and when I go to put it on, I notice that the Cat for bank 1 (Driver side) is on the other side because the exhaust crosses behind the engine...  I assumed that since it monitored the exhaust from bank one that it just plugged in on the other side of the engine bay.  I thought I was right because I drove it a few times with no light but on my way to Autocross last weekend, it came on again.  Before I start undoing stuff, do I have it backwards or does the car look at it as Bank1 if the sensor is plugged in on the Bank 1 side.  As anyone who has done this knows, it is a pain in the butt to get these in and out of a 996 GT3 so prior to subjecting myself to the discomfort, I figured I would solicit advice.  Thanks!!!

[clord]

Hi Oscar.....  I've recently had the same code for the same reason.  And as you say, the pipe/cat for each bank crosses to the opposite side and muffler.  In my case, I found a chaffed sensor wire that was grounding to the chassis.  I have a Europipe exhaust system and it's larger pipes/cats make it impossible to deal with the O2 sensors without removing the whole system.  Given that I was going to have to R&R the bumper cover and exhaust system, I decided to just replace all 4 O2 sensors while I was at it and not worry about it later.  The sensors already had 60K mi on them.  Good luck.

[JFP in PA]

16 minutes ago, OscarAH1W said:

Okay guys, I have been getting the CEL with this code for a while...  reset, drive a few times, no light... then returns on way home from Autocross...  So I order a post-cat O2 sensor and when I go to put it on, I notice that the Cat for bank 1 (Driver side) is on the other side because the exhaust crosses behind the engine...  I assumed that since it monitored the exhaust from bank one that it just plugged in on the other side of the engine bay.  I thought I was right because I drove it a few times with no light but on my way to Autocross last weekend, it came on again.  Before I start undoing stuff, do I have it backwards or does the car look at it as Bank1 if the sensor is plugged in on the Bank 1 side.  As anyone who has done this knows, it is a pain in the butt to get these in and out of a 996 GT3 so prior to subjecting myself to the discomfort, I figured I would solicit advice.  Thanks!!!

 

Let's start with the basics:  Year and model of the car, and what code are you seeing?

[OscarAH1W]

JFP-  2004 GT3 (This is the 996 GT3 forum, isn't it?) and the original (intermittent) code was P2096 Oxygen Sensor Ageing Bank 1.  It usually popped on the way home or on the first drive after an autocross.  I purchased the correct Bosch O2 sensor and replaced it with the understanding that the POST CAT O2 sensor for bank 1 plugs into the OPPOSITE side of the car, right next to the bank 2 PRE cat sensor.  After doing so, I still got a bank 1 O2 sensor light.  Thinking that somehow Porsche wired things differently I naturally looked at the other post-cat O2 sensor that plugs in on the driver's side of the engine bay.  In trying to figure out how to get at the sensor to replace it, I noticed that the weld on the output side of the Bank 1 Cat was broken, even though the exhaust was tight and not moving. (See Pic)

 

So I pulled that half of the exhaust off the header and easily got at the other Post-Cat O2 sensor.  After getting it welded, I re-installed it with everything exactly the same, now when I start the engine I am getting P0056 and P0161 Oxygen Sensor Heater behind Cat Conv Bank 2.  After all that , I am thinking that I was originally correct, that Bank 1 Post Cat O2 sensor plugs in on the passenger side, and I mistakenly put the bad O2 sensor from the Bank 1 side on the Bank 2 side. to troubleshoot the continuing code.  The CELs I got after the original O2 sensor may have been related to leaking gases due to the failing weld... especially as the bung for the sensor is about 12 inches from the cat.

 

Looks like I will be purchasing another post Cat O2 sensor (I ain't pulling it apart again to put an old one in, LOL.) and reinstalling...

 

CLORD, I see you mentioned a Europipe system... my cat has Europipe stamped in it... I really thought my car was bone stock when I bought it with 18,500 miles... thoughts??

[nickshu]

That is a Europipe cat. Mine broke in the exact same place on my 04 GT3. I just replaced it with a full Fabspeed Supercup system. Funny that yours broke in the same place.

 

 

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