Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help

Go Back   Pelican Parts Forums > Porsche Forums > Porsche 964 & 993 Technical Forum

LinkBack Thread Tools Rate Thread
Thread Post New Thread    Reply
Registered User
Join Date: Dec 2017
Location: CT
Posts: 5
Legally Pass Emissions with SAI Faults. Here's How

The following was posted on Rennlist. Hoping others here will try and benefit...

I began a quest this summer to find a solution to my SAI problem after failing my very first emissions test last June. Service records showed my car had a history of SAI problems with various "solutions" some legal, some not. My shop guy felt it was the air pump ($1500 part + install). I felt it was clogged ports. Could have been both. Regardless, I was looking at a major expenditure without any guarantee of success.

To make a long story shortÖI ended up passing emissions a few days later on a technicality that I stumbled upon quite by accident. A light bulb went off: ďMaybe this is repeatableĒ. So I bought an OBD2 reader and began studying how OBD2 worked, doing a number of drives of different lengths at different speeds, overnight cooldowns, start/stops, etc, with the goal being to find a way to reliably put the car into a state that legally masks my SAI problem anytime I wanted. The car is now off the road for the winter but I was able to come up with a simple procedure that does just that, at least on a 97 C2S 6 speed. Unless Porsche significantly changed the OBD2 system thereís a good chance itíll work on all 96-98 993ís.

A little background..Ö
OBD2 cars will "fail" emissions for 2 reasons. The first is if the required ďreadiness monitorsĒ are NOT READY. If you go to emissions in this condition they'll send you off to do the mysterious ďdrive cycle" and invite you back for another try. Note: All 5 readiness monitors always go NOT READY when you disconnect the battery or clear the Check Engine Light (CEL) Ė thatís why you canít just clear the CEL and pass. The second way to fail is if the way most people fail: OBD2 does its job and detects a real emissions fault, lights the CEL and stores the associated codes. You are sent away to fix the problem.

This SAI workaround hinges on two things. First, you donít need all 5 OBD monitors READY to get your car tested. For 1996 thu 1999 cars, DEP guidelines only require 3 of the 5 to be READY. Most states follow DEP guidelines (CA may be the only state that requires 4 monitors). Second, the OBD system canít flag an SAI problem until the secondary air monitor is READY. To exploit this all you need to do after resetting the OBD system is get 3 of the 5 monitors READY, making sure one of them isnít the secondary air monitor. If you do that, your SAI problem will go undetected. Simple and legal.

So how do you do that? Ö.
Get yourself an ODB2 reader, preferably one that can display all 5 readiness monitors on a single screen. While not absolutely necessary itíll be a helpful in the event you need to modify the procedure to work on your car. There may be other variations that work but start with steps below, following them EXACTLY. They have been tested multiple times on a 97 C2S and work.

STEP 1: RESET the OBD2 system using the OBD2 reader (or disconnect/reconnect the car battery). This will clear any faults and make all 5 monitors NOT READY, which is want you want. Do this the night before or right before starting the procedure.

STEP 2: Find a place to drive a minimum of 20 miles at less than 60mph and less than 3000 RPMs. 55 in 5th gear works fine. Cruise control helps. I believe this can be done in different segments provided the car isnít turned off until the 20 miles is completed, but to make sure, start out by doing it all at once. Itís faster that way too.

STEP 3: Turn car off, remove key, restart. Donít let the car cooldown. All 5 monitors should still be off. May not be necessary to remove the key but thatís the way I did it. I let the car sit for at least a minute before restarting.

STEP 4: Repeat steps 2 and 3
All 5 monitors should still be off.

STEP 5: Repeat step 2. Somewhere between 13 and 18 miles into this leg the CAT and O2 Heater monitors will go READY. Sometimes EVAP goes ready at the same time. If not. Do step 6.

STEP 6: Come to a stop without turning the car off and idle in neutral until the EVAP monitor goes ready. This should take less than 5 minutes. You now have the required THREE monitors ready.

7) Go to emissions. Be happy.

Sounds complicated but it basically comes down to three drives you can complete in about an hour and a half. There may be other variations that work such as shorter runs, different speeds, etc, but rather than wait until next spring to find out, I thought Iíd put it out there for review and comment. A test is worth a thousand theories and a thousand tests are even better. So Iím hoping a little ďCrowd TestingĒ will reveal how useful this is across a larger sample size of 993ís.


- You should do emissions right after step 6, preferably without letting the car cool down. In every test I did the AIR monitor went READY on the first cold start after completing step 5, and then the CEL tripped 12 to 17 miles after that. Donít know why, thatís just what I observed.

- Check with emissions in your state to verify they only need 3 monitors ready. A partial internet survey of DMV sites seems to indicate that all states except CA allow this.

- If you live in CA thereís still hope. Youíll just need to go a step further and find a way to also get O2 monitor ready before the Air monitor. This is one of the things I didnít have time to test this year.

-If your OBD is throwing codes unrelated to SAI, the same approach may work with a different sequence: just find a way to get at least 3 monitors set that arenít related to your particular fault.

- The OBD2 reader I used was an Autel AL519 (Amazon, about $60).

Looking forward to the feedback.


Old 12-14-2017, 08:43 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Registered User
Join Date: Feb 2008
Posts: 338
Thanks for sharing this.
The directions gave me flashbacks of programming my immobilizer...

The only thing I can add is that in some states 993's are already becoming exempt from Inspection all together due to MY age. IIRC, 1995 993's are already exempt in NJ for example.
Old 12-21-2017, 11:55 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
Registered User
Join Date: Dec 2017
Location: CT
Posts: 5
Yes! Something like 5 or 6 of the states that currently test will no longer require it once cars get to 25. My state (CT) is one. We test every 2 years so I still have 2 more. No worrries with this workaround, though.
Old 12-22-2017, 04:51 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
Registered User
Join Date: Apr 2018
Posts: 6
random/multiple cylinder misfire

do u think your same sequence would work with random misfire?
Old 05-29-2018, 07:18 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)
Registered User
Join Date: Dec 2017
Location: CT
Posts: 5

If I understand your question correctly, no. The concept behind the workaround is that ODB codes are blocked until the readiness monitor associated with it goes READY. In the case of SAI-related errors that's the "AIR" monitor, which after a system reset (or battery is disconnect) won't go READY until the conditions required to set it are met by driving around (the mysterious "Drive Cycle"). That opens up a window of opportunity - get 3 other monitors ready (4 in CA) before AIR and you can get tested and pass even with a totally shot SAI system.

The MISFIRE monitor on the other hand is what they call a CONTINUOUS monitor which means it's ALWAYS READY, (ready to throw codes), even after a reset. So there's no opportunity to play the same game.

FYI - It turns out it's pretty easy to get at least 3 of the NON-CONTINUOUS monitors READY while avoiding AIR. In addition to the drives described in the first post, the attached shows what I ended up with the other day just driving around normally.

Old 05-30-2018, 04:49 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #5 (permalink)

Thread Tools
Rate This Thread
Rate This Thread:


All times are GMT -8. The time now is 11:04 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.