California Exhaust Question - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Looking for advice for exhaust info for 2001 Boxster S ( 4 Cats). I want my car to be legal and i bought headers for it which have two O2 sensor ports each, but I need to know if I can replace the to stock cat’s with just two and still have it pass California Smog tests…? Also, did I mention that I don’t want to spend a ton either for it…

Your car is unlikely to pass smog. You're probably going to get a MIL (check engine) light because of the headers (you can't pass smog with a check engine light). If you wind up at a shop that knows anything about your car, you will also fail the visual inspection. I have no idea if you'll pass the tailpipe sniffer. Unless the headers you bought are CARB certified (and I can't imagine they are), your car will not be smog legal. Tampering with the emissions system, especially in the People's Democratic Republic of California, is a no-no. If you haven't already installed your headers, save yourself the hassle and sell them to someone else...

Technically aftermarket headers are not street legal in Commiefornia but if nobody looks at them, they don't throw a CEL, and you pass the sniff test you may pass smog inspection. Your primary O2 sensors need to be pre-cat, and your secondary sensors need to be post-cat. With a good set of cats your car should run clean with no CEL. I would probably save the headers for a dedicated track car and sleep better knowing that the KGB wouldn't show up in the middle of the night and impound my daily driver.

Well put, Topless. However, OP stated "I want my car to be legal." Even if he/she passes the emissions test, the car won't be legal if non-CARB-approved equipment is installed.

With two O2 sensor ports on each side, this header might be able to pass the smog test fairly easily because the computer will be able to adjust the air/fuel mix to minimize emissions.You'll need all four O2 sensors (pre and post cat) for the ECU to tune the air/fuel mix properly to pass the emissions test. If you get rid of the post-cat O2 sensors, the engine will run fine but the emissions might fail the test. If you do this, be sure to drive the around for 20-40 miles in varying conditions to get the ECU to fully adjust for the header change. Its unlikely that the test tech is going to get under the car to do an actual visual inspection of the headers and even less likely that he'd know what he's looking at. With all of that being said, you'll have to check with the header manufacturer to find out if their product is CA approved. If not, then its technically illegal but you still might be able to pass the smog test.

There are a number of things you can do to make the car pass the sniffer and not have any codes.... However if anyone does a visual and knows what the car came with before, it is a automatic fail. As a past tester I am required to see and check that all 4 O2 sensors are there, as well as all 4 cats and if the cats were replaced in the past it must also have the proper tags to say they are legal in the state.

Just to be clear: Do you want your car to be legal or do you want it to pass smog? Because hoping that your car is legal after installing illegal exhaust hardware is an oxymoron....

Reviving this Thread rather than starting a new one - couple of things - 1) I'm in CA and have not even CONSIDERED changing the headers due to CA smog laws. I HAVE changed the exhaust and, in fact, since there isn't a O2 sensor on the secondary cats, I put a test pipe in and it runs great. 2) Since CA doesn't sniff anymore on certain model years (including my 2000 S), that 2nd cat's weren't an issue. And I have a guy that is WAY to lazy to get under my car to check, so I'm good with visual 3) This got me to thinking about headers. And since my boxster is mainly a track car, I'm thinking of putting them on (research tells me they DO make a difference on our cars). Question is - for those that have headers, and especially those that have headers in CA - 1) What all is involved in KEEPING the primary cats and O2 sensors with headers? Is it a big project, or pretty much plug and play? 2) Do you feel the performance improvement and potential new life of crime is worth it? Thanks for your input!!

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I don't have an answer to your question but can you elaborate more on item 2? My 02 is due for registration and it states it needs a smog certificate.

Quotes source post: 452683

They do not use the tail pipe sniffer anymore but plug their computer on the OBDII port and run the tests through a software. They don't even kneel anymore at the back of the car so less and less chances that they find out if you installed cat pipes / headers.

Quotes source post: 452685

Yeah, exactly what I was thinking!

We do smogs and yes we open the engine cover as well as look under the car. Visual is legally still part of the inspection.

Does Porsche sell a CARB legal header and a different header that is legal in the other states. From what I can see, they cite one part number 01S and I've been assuming its legal in all states.

Quotes source post: 452693

I do not doubt about your professionalism, don't misunderstand me. The local places where I lately smogged my cars didn't visually check, they used the OBDII port. Some places refused to smog the 986 though because they couldn't "have a look at the engine"...

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Thanks. It's been two years since I last smogged any of my cars and I have 4. That cycle is this year and I already have two to smog. I'm not sure of this method is easier to pass or not.

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I'm just saying legally they are supposed to look and do a visual inspection. We look, especially since they have been cracking down on our area here. We charge extra to remove the covers to inspect. We do other more exotic cars. What's funny is some of these car sit so long or they actually remove the connection to the battery so that they can be stored long term with no ill effects ie. Battery drainage, but this removes all the readiness tests , this means they have to drive the car until the tests are complete. The smog inspection cannot be performed if the readiness tests are not complete. You should see the look on their face. They have to actually drive their low mileage Ferrari or Lamborghini! What a horrible thought! I keep offering my services to drive their car until the readiness test are complete, so far it my offer has not been taken. Although it has come close, a couple people have come back several times without the readiness test complete. It must really suck to be forced to drive your exotic car. Sent from my SAMSUNG-SM-N910A using Tapatalk

How long do you have to drive the car to complete the readiness test?

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OMG that picture is humongous! Sorry Normally less than 100 miles but however long til the tests are done. it can be as little as 30 miles. Honda actually has a program to force the tests to be done. Too bad its just for Honda. Let me see if I can fix that picture... Fixed!

And if it were me I would get one of the cheap testers to monitor my car to see if the tests are done yet.

My bank 2 cat is nearing the end of its life and it occasionally throws a CEL with accompanying code. Because I was facing a smog these this coming summer, I done some homework. First, every SF Bay area smog test station I took the car to told me the same thing. CA is very serious about shops doing complete tests. This meant hooking the computer up to the diagnostic computer to check various systems. Second, every shop insisted on that they perform a visual inspection of the top of the engine and the exhaust system. They also said that all monitoring systems must have ready status except the EVAP system. I plan to replace the Bank 2 header with integral cat soon. The question I asked above, perhaps poorly, is: are all Porsche OEM header / catalytic converter parts CA legal or does Porsche sell one of CA and another part for the rest of the US. BTW: my cheap tester cleared the CEL light, but didn't clear the stored code. The Durametric took care of that.