You may have already entered SAI hell. I have. There is more to this issue than just replacing parts, doing the drive cycle and fitting an SAI emulator to test your work.
The hellish part is called "Not Ready" or "Inc"= incomplete. This is the fault that causes you to fail smog even if there is no MIL.
If you read here and on Renntech you will find loooong threads where smart guys flounder at solving this issue.
I am not so smart and I was a contributor to these threads. Eventually I passed the Test but almost immediately the MIL came back on. But I got my Sticker !
2 years later and I still haven't fixed the MIL so I fit an Emulator. Light goes out but the SAI System shows "Not Ready" = FAIL on Durametric, Foxwell and the Smog Station's DAD test machine. They note that the entire SAI system is complete and seems functional. So they say - just drive it ,eventually it will set "Ready". Not yet -after 800 miles 1
So what is next to fix this SAI system ?
To do the diagnosis comprehensively and check your repair, you need a vacuum pump and a means of monitoring the PRE-CAT O2 sensor readings at start-up for 90 seconds.
1. Don't fit an ROW reflash unless you are promised a refund if the DAD machine detects tampering.
AFAIK an ROW reflash is detectable and you'll be having a very expensive meeting with the Referee.Otoh , it may be smart to have a stock reflash done. A PWIS tool may be able to set a 'sticky' monitor.
2.Take off the psngr side inlet manifold per the youtube link I have given in previous Threads and replace every component you can reach.See Porsche Parts manual or Auto Atlanta online for parts diag.
3.Consider cleaning the exhaust ports into the heads Ugh ! Search for details.
Most Important - NOTE -the system changed with the later cars. Ignore all the photos earlier in this Thread until you
check the Auto Atlanta parts diagrams for dates and details. Don't buy any part until you know which system you have.
Testing/replacing the Secondary Air Pump is easy. There is a similar,cheaper Mercedes SAI Air pump with a nearly identical Bosch part number. No clue if it fits/works.Others may chime in to confirm?
Replacing the other parts is tedious because you need to remove the passenger-side intake manifold. Maybe other parts for access. It is easy to break brittle plastic hoses inadvertently.That means you may succeed in the repair but have to go back again hunting for hairline cracks in the corrugated AOS hose.
4.Keep screen shots or notes of everything from Durametric tests particularly O2 sensor voltage changes during the first 2 minutes after start up.
5, Find on Renntech all the preconditions to set the SAI System as "Ready". Do the Drive Cycle and keep logging the data.
6. Make sure all related systems are functional - O2 sensors, AOS ,ignition system. Otherwise you'll get hopelessly deceived.
7. Replace all the hoses with best quality USA made silicone.Replace all the hose connectors with brass fittings.
8.Note that the '01 and '02 MY is notorious for this 'Not Ready' problem .Same issue for E39 BMW -search "E39 Smog not ready" for more.
Before you refit the Intake Manifold ,test the SAI system. -not just the components, the whole system - electrical,vacuum and SAI air flow. The limitation is you can't run the engine until you refit everything..
Here's the only way I know of testing at the Shut Off Valve for flow/vacuum with the engine running at cold start. Why is this significant ? -because suppose all the components tested 'good' but there is still a failure to get rid of the Check Engine light .
To allow testing for vacuum at the ShutOff Valve with the engine running at cold start , add some vacuum hose via a Tee - after the Change Over Valve(before you refit the Manifold!!). Fit a Brass Tee on the output side of the 12v Change Over Valve. Run the hoses up between the runners of the Intake Manifold. If you don't need it ,you can just plug it. Now you have a hose end to connect a vacuum pump to or a Vacuum gauge/manometer(or your finger tip) to measure vacuum and test the system.
You should should see strong vacuum(12"+Hg) to the Shut-Off Valve at cold-start only. It should collapse when the SAI pump stops running(60-90 seconds). If there is no/insufficient vacuum, the Shut Off Valve will not open to allow SAI air from the pump to enter the exhaust stream.
To fix a problem, you can bypass a vacuum/electrical defect by fitting an extra Change Over Valve+ made up harness ON TOP of the Intake (where it should have been from the factory !!)
If/when you no longer need it just connect the 2 extension hoses together with a 3 or 4mm straight barbed coupler.
If you are clever you may even fit the extra Change Over Valve on top of the Manifold with new, bypass wiring via a
manual switch .That way you can manually turn on the SAI vacuum and Secondary Air flow for 60 seconds at start up for 3-4 times to prepare for the Smog Test.
Check your repair by monitoring the sine/flat wave for the O2 sensor voltage at cold startup.
If you remove the Inlet manifold -you may need to remove the Serpentine belt(but not alternator) to access the 6th bolt.
When replacing the 6 bolts remember to use Green Loctite .Use "Earthquake Hold" or a very good magnetic 10mm socket insert or neodymium extension to get the bolts started. It is very easy to drop one !
If you still get "Not Ready"or "Inc"-omplete for SAI and the engine is unmodified, take your Smog Failure Certificate to the Referee(in California) and get a waiver. They will pass it and give you a certificate IF you haven't done any hacks. Hopefully a test vacuum hose wouldn't be considered illegal. Be warned, they will scrutinize everything !
For the 'rest of the story' ,read here:
https://www.renntech.org/topic/55085-not-ready-sai-secondary-air-incomplete-smog-test-fail/
If the problem is just no CEL but "Not Ready" try starting the car from cold and running for 90 seconds at 2000rpm+/- 300rpm. If you run at 2800+/- 300 rpm you may get a CEL.This worked for me and got me to pass Smog.
If your O2 sensors are marginal consider replacing all 4 with the same brand. I used Bosch.It seemed to help. The other suspects are old primary cats. We'll assume all the vacuum components are perfect and new by this stage.
Hope this helps you and others who follow.