I have a CEL that the dealer says is caused by a Bank 2 Cat efficiency problem on my 2000 C2. They are saying that I need new Cats for my emissions test in April. I was looking under the car to see where the sensors are and whether it is something I can do mayself but it raised more questions.
1)When I looked under the car, there is only on sensor on bank two before the cat. Isn't there supposed to be a sensor downstream of the cat as well?
2) How does a single sensor upstream measure cat efficiency?
3) Is the dealer feeding me a bunch of bull and the real problem is just the sensor?

Looking forward to your thoughts. Thanks

 

There are two sensors on each cat, pre and post. The ones you can't see are located at different spots, you can try removing the airbox and looking down from above.

 

Correct... there are 2 sensors on each cat.

 

Thanks Guys....I'll take a look when I get the car out of storage

 

I had same problem. I see two new cats in your future.

I found a pair is 997 cats which fit, with some additional tubing.

I recommend you start looking......

Jb

 

There definitely two sensors on each cat, and if you haven't got rattling yet from the cat, you will before long. Now you have a couple options, you can find a used cat and hope its still in good condition or a new cat oem or after market cat $$$$$$$ also there are things out there called o2 sensor "spacers" or "c.e.l eliminators" that you can buy at any online performance store or even ebay anywhere from 5$- 45$ depending on material used, that go in between the cat and sensor. The way it works is ,there is only has a small hole in it and only allows a small amount of exhaust into the sensor fooling it and therefore eliminating the c.e.l light because the computer believes the cat is doing its job. Another fix which is what i did, is buying a "cat by-pass x-pipe (FABSPEED) that has no cats at all and using these eliminators to keep your light out, and with that you give your Porsche a little more power and a great exhaust note.

 

It may be the cats...but I suggest a bit of sleuthing on your own first, before opening your wallet for the "stealer":

1. Copy down the code that caused the CEL (many auto parts stores will read your codes for free, or buy and use a Durametric). Clear the CEL (use a Durametric, or disconnect the battery for 15 minutes). See if the CEL reappears, and if it does read the code(s) again. If it is the same code then you likely have a real issue and read on. If not, you're golden!

2. Sometimes the issue is a failing post-cat O2 sensor. To figure this out, swap the sides on the post-cat sensors. Clear the CEL. If CEL reappears and if it's the other bank that is now "bad", then replace that post-cat sensor which is an easy DIY repair. The part is a couple of hundred bucks IIRC. Get a special O2 sensor socket, which makes removal/reinstallation of the sensor much easier.

3. If, however, the CEL reappears and on the same side (after swapping the post-cat sensors) then you probaby have a failing cat. If that happened to me I'd opt for aftermarket sport cats; might as well squeeze a tad more power and a much better exhaust note if I'm going to replace the cats.

FWIW, I had a CEL for bad post-cat sensor appear back in November. Cleared it with my Durametric, CEL-free since. Other threads on this and other Porsche sites report similar instances of spurious CELs. So it may be nothing.

Good luck.

 

Thanks for the super useful information. One question though....I have been able to locate the precat sensor right at the bend coming from the headers but I have not been able to locate the post cat sensor. Tried several times and could not find anything. WHere do I locate them. I see nothing down stream of the cat.

 

I bought a obd meter and clered my CEL. Will I be able to pass inspection?

 

No as your readiness is cleared when you clear your check engine light. Your car will need to be driven for some time (50 miles or so should do the trick) During this 50 miles your ECU is looking at all parameters to make sure they are in check for what is it programmed to see (In your case if your cats are doing their jobs or not). After this 50 miles or so your cars readiness will be set again, and then your car is eligible to be inspected/pass emissions.

If they try to scan your car to pass it for emissions it will fail as your readiness is not set.

My advise if you are trying to pass and a quick fix that will not cost you 1k+ would be to get 2x o2 sensor spacers like this one:
http://store.42draftdesigns.com/O2-S...cer_p_306.html

Install these on both the post cat o2 sensors and your ECU will be tricked into thinking the cats are doing their jobs. As long as they don't physically see these during the inspection you should be able to pass.

Keep in mind your cats are still bad, and they could get clogged in the future. I would replace them with either a pair of high flow cats (Still legal, but not as much as the cost of OEM cats) These will open up some power and sound on your car. Or just go test pipe route and keep the o2 sensor spacers installed. Your car will not be "legal" but unless they are really looking for them it should pass.

 

Those spacers are a great option to clear CEL code from cats.

 

Wow...thanks guys....great information. I already have one spacer cause I thought I would only need one. For the post cat sensor on Bank 2. Are you telling me I need one on both post car sensors on each side? Even though I have a code one cat? So here is what I see as my options based on what you guys are saying.
1) Drive 50 miles and see if I get the CEL back.
2) If that doesn't work, I can try the spacer (s)
3) Next is get new cats... I have two options there...HJS Sport cats that Cantrell will install for me here in Seattle area (total cost of about $1500). A second option is buy the stock cats that White Out offered me at much lower.

Really appreciate all of the knowledge you guys are sharing. I have until the end of April for inspection.

The frustration is I pretty much only use the car for the track but need to have it registered and inspected to drive to and from....

 

With only one dead cat, you should only need to run the one spacer.

 

Thanks white out

 

You guys were right about the CEL... back after 40 miles. Will try spacer tomorrow if weather is good