TSB UAOS "Slow Flash"

It has been determined that 1-2% of the installed UAOS Sensors can be too sensitive to water vapor or steam produced by the engine and can activate the "slow flash" warning when no accumulation is present.. The UAOS System is designed to be much more efficient at separating air-oil mixture from the blow-by gasses to keep them from going into the engine to cause harm,( it also reduces Emissions).. All combustion gasses have about 13% water vapor or steam. The water vapor/steam in the blow-by gases are allowed/intended to go on into the engine to be recycled and reburned to eventually exit through the tail-pipe. This water vapor/steam also reduces NoX emissions by reducing combustion chamber temperatures, and the water content contains 33% oxygen that the DME is calibrated for, for correct fuel trims.. On some higher mileage engines or on new engines that have not fully seated the rings there can be an excess of water vapor/steam going through the Accumulator that can be detected by the laboratory grade UAOS Sensor.. Corrective Action ::: I have found through testing that the Sensor can be made less sensitive by marking the installed position at 12 o'clock ,unplugging the harness and remove the sensor, coat the tip of the Sensor with a Ceramic Wax, add another rubber washer and re-install indexing the new install position at either 9 o'clock or 3 o'clock position... This keeps the water vapor/steam from forming droplets of liquid on the bottom/Sensitive area of the Sensor.. UAOS Microprocessor Controlled Infra-Red Sensor Diagram The Stainless Steel/Glass Sensor used in the Elite kits is not effected by excess water vapor/steam so no corrective action is necessary for it and it will soon be discontinued as it is overkill for our application on M96 engines with a pressure rating of 600bar/8700psi...... A new laboratory grade Polysulfone Microprocessor Controlled Infra-Red Sensor made by SST Sensing in the UK specifically for our m96 UAOS application will replace the Stainless Steel/Glass one on Elite kits and all Standard kits also...I have a few of these on hand and once the supply of the old ones is depleted these new less sensitive Sensors will be used in all UAOS kits... Diagnosing the "Slow flash" ( once per second) :: The Slow Flash warning in the dash can be caused by three different systems.....The low coolant system, the engine compartment temperature system, and the UAOS system.. 1. low coolant switch ; if the coolant is low by only a few ounces, the slow flash may come on intermittently at times. 2. engine compartment temp:: if the engine compartment temp gets above 185F, the slow flash will activate. If the temp sensor (located in intake manifold between #4-5 runner in rubber grommet) is dislocated and fell on top of engine it will slow flash, of if the engine lid fan is inop. 3 UAOS Sensor :: If equipped with UAOS, the slow flash will activate if the accumulation reaches 120CC .( drain accumulator, unless you have the high-mileage/Extreme Track Duty Auto Drain). When diagnosing the "slow flash" always start with the obvious. Level 1 diagnosis ;; a.Check the coolant level, b.check the engine temp sensor mounting, c. drain the accumulator (if UAOS equipped NOTE:: not necessary you have the high-mileage/Extreme Track Duty Auto Drain) Level 2 diagnosis a. disconnect the low coolant switch at the bottom of reservoir and leave unplugged and road test. Results: if slow flash stays off , problem is in the low coolant switch, if slow flash remains, continue to (b). b. Leave low coolant switch disconnected, and disconnect UAOS harness and leave dissconnected . result: if slow flash stays off , problem is in the UAOS harness/sensor, if slow flash remains, continue to (c). c. Problem is in engine compartment temp circuit .;; check deck lid fan for obstruction and proper operation. Level 3 diagnosis; this requires wiring diagrams, a DVOM, a good skill level and understanding of Automotive systems. a, test low coolant circuit b.test engine compartment temp circuit c. test UAOS sensor./harness

This is what happens when you beta test "production" products advertised with support run through internet forums. https://rennlist.com/forums/996-foru...v2-2-a-58.html

You should see the stack of "TSB's" that Porsche and all other MFG's send to their Techs every month !! Yes, it is unacceptable and is why it is now improved !!! Also the new AIM MXS1.3 Data Acquisition System I just bought for over $3k has a list of updates as long as your arm. !! lol ...so GTFO with your trolling self..

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Thanks PT3! No slow blinks here.

Yea, Houtx996 has flawed logic, he is OK with a 1-3% failure of a ball bearing that can take out your whole engine, but is critical of 1-2% "Slow Flashing light " that causes no harm...lol

for us uninformed folks, what is ceramic wax?

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https://www.walmart.com/ip/Meguiar-s...B&gclsrc=aw.ds

Thanks for this Skip. We are firing ours up on Tuesday.

My car was in that minority of cases where the low coolant warning light was going off prematurely with the UAOS. Skip worked with me for a couple of months testing harnesses, testing a new sensor, and then finally sent me the glass sensor to try. That did the trick. My hat's off to Skip for his support. Now if winter can just leave New England so I can get the car out and drive...

Hey Skip. Mine has this issue. Doesn't bother me since I have the drain back, so I know it is not full and I can just ignore it. Can I just unplug the sensor from the harness since in theory, it should never be tripping the sensor?

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Yep, thats what I did!

Hi Kris, I know it sounds like "overkill" when you have the track drain, but I just had someone who has the UAOS with Track drain, and he accidentally installed one of his scavenge pumps backwards and it set off the warning at high RPM , so he drove carefully home and called me....We figured out he installed the scavenge pump backwards and it filled the head with oil and even enough to set off the UAOS Sensor !! So the warning Sensor saved his engine in two ways... I spent a lot of time and effort designing it so Please leave it on...lol Just mark the Sensor at 12 O'clock and unscrew it, put a coat of Ceramic Wax on it and make sure to re-install it at 9 O'clock or 3 O'clock position... Cheers !! You Tube You Tube I had a couple more video's where I tested them with water vapor/steam created by a hot plate...but some how the video didn't turn out..

Thanks Skip. I've had the issue for quite awhile and will try your workaround if it ever warms up around here again. I don't have a heated garage to work in.

Good deal Bill, yea it was quite a challenge to figure this out... None of the cars here in Bama have had this Phenomenon... I feel like I have done more testing on the SST Sensors than they have...I think I have even shown them how to make better Laboratory Grade Sensors... ( at least for our cars...lol)

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Thanks for this TSB. Imagine if the OEM suppliers or Porsche themselves made such things available to the public the forums would blow up. Your post is yet one more reason that I'm spending my money on UAOS. These cars are are expensive if you let them go. I'm trying to make mine a reliable daily, and the factory aos appears to be a point of failure. I'll make sure my Indy is aware before he installs. Thanks! ​​​ @Porschetech3 any chance you're going to blow out the elite kits at a discount?

I have a UAOS waiting to be installed. Is there anything preemptive that can be done pre-install that can prevent this from happening?

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Porsche and other Auto MFG's are only interested in promoting and selling their New Models Cars.... Their "Motorsports Division" would be the only interested parties... The Elite kits are all sold out and since the Stainless Steel/Glass Sensor will no longer be used, the name will change to "OEM kit" and still use the OEM Audi/VW flow regulator ( with OEM tax..)... You could remove the Sensor and put a coat of the Ceramic Wax on it with an additional rubber washer and hand tighten it and mark it at 12 O'clock........Then if there is any false warning or Slow Flash just tighten the sensor another 1/4th turn to 3 O'clock... That should take care of it... The installed position/index is the most critical..

Skip, anything I need to do with the UAOS Track version? Cars at the shop, might as well make adjustments if needed.

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Nope, only 1 or 2 out of 100 will have this Phenomenon.. Yours is already installed and working perfect... I will be "indexing" all the Sensors on new builds until all the old style Sensors are used up... the New Sensors will not need indexed...

I've been dealing with the slow blink for 3 years. I can't reach the plug without removing the coolant tank and I'm not in the mood to deal with that right now. My car is an MK-I Tiptronic Cab, - I don't know if that makes the job harder but there is no way to access the sensor. My hands and wrists look like I've been fighting with a bobcat. Can I cut one of the wires coming from the UAOS that will eliminate the false alarm but keep the original coolant level alarm intact? That way I would stop it for now and fix it properly down the road.

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Hey Bill I feel ya my arms get all cut up easily now. The older I get the thinner the skin is.. I have found that removing the SAI pump is the only way for me to get my big *** hands in there to the low coolant switch... The Sensor only has three wires, a red (+) a blue (-) and a green ( output) , cutting any of them will shut down the UAOS warning but the green is the one that actually outputs to start the slow flash.. Cutting any wire in the UAOS harness will not effect the low coolant warning, only the UAOS warning... I have only had 1 bad sensor returned, all others have tested good but they are very sensitive to the final installed position...hence the "indexing" and now the Special Sensor made just for us. And wouldn't you know it, the new special Sensor even being less sensitive costs twice as much as the more sensitive sensor...I suppose because we will be the only ones using it...Everyone else wants the more sensitive one...

Thanks, Skip. Just to confirm. I can cut the green wire in the bundle coming from the UAOS sensor without affecting the actual low coolant warning? And if the slow flash persists afterwards it means there is a problem with the low coolant sensor. I did test the coolant sensor using a magnet and a continuity tester as you suggested before I reinstalled it during the tank swap. I did remove the SAI pump but still couldn't get my hands in there. Thanks again!

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Bill, since you are having difficulty in getting to the low coolant switch to disconnect the complete harness, you can drop back 3-4 inches from the Sensor and cut all three wires and install bullet connectors. That way you can mark the 12 o'clock position then unscrew the Sensor coat it with Ceramic Wax then install an extra rubber washer and re-install to 3 o-clock or 9 o'clock positions and then reconnect the Sensor..Cover the bullet connectors with a length of 3/8 split loom cover or something to make it look nice.. This is the same as done on the 993 A/C harness where there are several Sensors that are made into the harness and when one of them needs to be changed the new Sensor comes with a length of wire made into the Sensor and the Tech has to chose a method to use.....I always try to make it as less conspicuous as possible ( but functional/practical) and Factory nice looking..

Do you know what gauge the wires are?

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The wires are 24AWG and are ridiculously strong for their size...

Great thanks!

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I may have been the one that returned the harness to you after the slow blink. I installed your new harness and zero issues with it until today. It�s prob 90+ degree out, and I had a lot of idling in traffic for a while, but the slow blink started again. I�m letting the car cool off for a bit and then taking it out tonight. Coolant level is good and there is nothing in the catch can. Car just hit 103k miles.

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In your case you may have the engine compartment temperature getting too high and causing the slow flash....... I have had customers who complained of the slow flahs happening at bank drive-throughs and falsely thought the UAOS Sensor was causing the slow flash........after it was nailed down it was the engine compartment temp Sensor that was laying on the engine and not installed where it should be in the gromet in between runner 4-5.. The key here being you comment " sitting in stop-n-go traffic"...

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Yup. It was a **** drive. Strangely hot today. Construction everywhere. Heading out now. Hopefully that was it.

May totally be my imagination but with the spoiler up ,,,, It seems like in stop and go it stays cooler in the engine bay the fan seems to run more on ---- off------------ on ---- off

All good Skip. No issues. Must have been the heat. Thanks.

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Hi Skip. I did as you recommended and so far so good.

My car is experiencing this only during a cold start. The light disappears after warming up, getting turned off for about 5 minutes, and then restarted. I struggled to find a comparable rubber washer like the one included and was hesitant to use a nylon washer in addition to the rubber washer because I wasn�t sure if it could create a vacuum leak. I did find that the one included in this Do It Best sink aerator set (#407857) is not only a perfect size, but double the thickness too. So I removed the original rubber washer and used this one instead by itself. Just wanted to post this in case anyone else was looking for a solution.

Happy to report that the TSB worked for me and my 9/98 build. Good work Skip.