A wierd one... PSM and ABS lights come on

Hi everyone. I'm pretty new to the forum, but not new to Porsches. I currently have a 2001 996 Cabrio that I've been doing some minor mods to. I put Fabspeed MaxFlo mufflers on, the K&N CAI, and then a Unichip. I did them all in stages to make sure each worked before the other. A few weeks after everything was installed, I got the dreaded CEL. I tried resetting the ecu, but the CEL came back so I removed the Unichip to see if that was causing any issues. The CEL again came back with the stock ECU so I took it to my local and very respected independent Porsche shop. They said the CEL code was that the left bank longterm was too lean and they reset it and said if it returns in 50-100 miles, it's likely the mods, specifically the intake. However, here's where the fun starts. On the way home from the shop, the first time I got on it and went over 5 grand RPMs, the PSM Off and ABS lights came on and would not go out. I pulled off the road and shut it off and back on, and they stayed out until the next time I got above 5 grand or so RPMs. I tried disconnecting the battery just to see if it wasn't a glitch from resetting the CEL code, but it continues to happen everytime I go above the magic mark on the tach. Sorry to be so long winded, but I wanted to include all the details I could. I'm baffled by this one and wanted to see if anyone has come across this, before I take it back to the shop for more money out of my pocket. Any help or ideas would be greatly appreciated! Thanks!

Happen to stumble across this thread... Sounds like the issue and was MAF related. https://rennlist.com/forums/996-forum/287012-pse-off-and-abs-lights-come-on-under-wot.html

Sounds like MAF to me too - I had the same codes and after the bonehead changed all the O2 sensors, he figured out it must be the MAF. Buy the part and do it yourself. It is an easy install.

Yes that is typical of the POS MAF!

Excellent... sounds like the issue exactly. I'm going to try taking out the MAF and spraying some CRC Electronics cleaner on it and see what happens. Hopefully that's all it is. I called the local Porsche dealer to get their thoughts and they seemed to think it was a wheel speed sensor and were already talking $400+ to replace. If that ends up being what it is, I guess I'll have to go that route, but if it's just a dirty MAF, I would not be too happy to spend all that only to have the problem return on the drive home! Thanks again... will keep you posted!

First did you ever get the codes read? If so what are they...we can help better knowing them. If you already got the ABS/PSM and a CEL the MAF is blown and no amount of cleaning will bring it back...sorry. Buy a new one ~$240 and install it yourself. Now why it blew...do you have stock intake and dry filter? If not I would suspect those items first.

Would someone please enlighten my amateur mind a little? If the issue is with the MAF sensor(air intake), why did the ABS/PSM (brakes/wheels) lights come on?

Perhaps you should contact Porsche directly for the answer to this bizarre event. Unfortunately it is what it is. Read the codes!

Translation... Knowledge is power: You will be in a much better position for receiving relevant answers from the forum with the ODBII decoding information. Not to mention, positioning and perspective with the dealer. Just one "newbie" to another....

Well I disconnected the battery, took out the MAF tonight and cleaned it good with the electronics cleaner. I also cleaned all the contacts on the plug connectors as well. Took it out for a drive and it all looked like it was going to be good... couple hard pulls past 5 grand and no lights. Then on about the 4th hard pull in 3rd gear, just past 5 grand and there come on the lights again. I guess at this point either the oil from the K&N filter is getting on it and triggering the lights, or the MAF is shot. Do you think the dealer could have a point as well with the possibility of a bad wheel speed sensor? It just seems odd that this seems to be a common issue with those who've installed the K&N CAI. I guess I should have just stuck with the darn EVO one. Oh well, you live and you learn... Has anyone tried another cone style, non-oiled filter on their K&N kit, to see what effect that had on the situation? I'm thinking of trying that out as well. Wross, as for the codes, I did not get the actual codes back from my independent shop. All they told me was that the code meant that the "long term fuel trim bank 1 system was too lean." Sorry, I didn't think to ask for the code since they said to see if it came back in 50-100 miles. If it CELs again, I'll get the codes from the AutoEnginuity I just ordered and check here first before going to the shop!

I'd say it is not the wheel speed sonsor. It is a blown MAF (cleaning will not fix as I said already!). Get a new MAF and then decide if you want to stay with the upgraded intake or back to stock...either way I think dry filter will be a better choice. You can order MAFs here. Easy DIY install. http://www.autohausaz.com/search/pro...0Mass%20Sensor

I'd be damn...but thanks for the tip. I'm learning...I'm learning... The E39 BMW's have the same CEL realated to faulty MAF sensors as well. I wasted money on several unrelated parts, stressed out with the lights coming on again, finally I got some recommendations from the BMW forums and suggested to my mechanic before he tried borrowing one from another 540i that happened to be there in the shop and it worked. Funny thing is...the brand new MAF sensor that was installed failed on my way home from the shop! I was pulling out off an exit onto the highway and floored it....the whole engine just cut off. I was already in the fast lane, so I had to roll over onto the median. Replaced with another brand new one and never had problem since.

The ABS and PSM are more than likely a brake or wheel speed sensor,(esp if in combo) probably unrelated to the CEL or other mods unless the operating temp was excessive. Check under the front axel assembly with the car jacked up, see if something is dragging behind the rotor area, this is where the two sensors are located. Then check the sensor with a resistance probe, should read 1.0-1.5volts with a complete revolution of each wheel/rotor. Any decent indy should be able to do this for you if you're not mechanically inclined. C

It is the MAF - I just changed to the K&N Cold Intake and BAM ! now I get the same Errors - Without a doubt it is the MAF !

Yup, same over here. I have the K&N cold air intake. What I wonder though, is it really necessary to toss in a new MAF ? Could this in any way harm the engine, or is it just a warning light triggered by the fact that the MAF is now operating in a non stock environment ? Also, is this something that's going to continue to happen as long as we keep the K&N filters ? In that case we better start ordering new MAFs in bulk...or return the K&N filter. Seems to be they have not performed approriate R&D on this unit.

Wow, you got that right, Yves. I put a K&N CAI on my truck about 2 years ago and that's why I went with this one over the EVO. The one for the truck was the easiest and best install of any aftermarket product I've ever done. This one was far from an easy install with half the parts missing and the diagram being drawn for viewing only through a microscope. If it's the oil on the filter causing this problem, I doubt any R&D was put into the product. I'm going to check the codes once my reader comes in and if it says it is the MAF, I'll order one from the link Wross gave... seems to be a darn good price. I also just ordered an AEM Dry Flow non-oiled cone filter to replace the K&N one, to take yet another precaution. The part number for theirs that seems to match up closest to the K&N that came with our kit is the AEM 21-204DK one. I found one here at AJUSA: AEM Cone Filter Once again, I'll keep you posted!

I guess I have to pile on here too. I had the exact same problem (and symptoms) as sfirestine yesterday and I just got the call from my indy...it's the MAF! So the question I immediately have to ask myself is whether or not this is the K&N CAI (which I have had on since mid-June and 1K miles) or just a coincidence? Jeff

The coincidences just keep adding up...intakes can be a problem (either aftermarket systems or filters). Of course much depends on other mods, environment and driving habits...but well you can guess the rest!

So let me run a financial analysis on this one : - K&N kit : 300$ - Replace MAF : 250$ - Buy other cone filter : 50$ =>The K&N cold air actually seems to cost 600$... Something doesn't make sense over here. There such a thing like product liability (especially in the US). Anybody up for contacting K&N and submitting an official complaint ? Let's try to make a tally of number of occurances on the K&N product. Anybody who's up for it, please chime in.

That's exactly what I was thinking! And I would assume the MAF would go bad again soon in the near future. It makes more sense to just stay away from K&N I don't think CAI's give enough, if any, hp improvements to justify the costs.

The ABS and PSM control units rely on inputs (engine speed, torque, etc.) from the DME control unit so as a safety precaution the ABS and PSM will shutoff when the DME control unit registers a fault. With a PST2 or PiWiS it will show up as fault code 5540 when interrogating the PSM control unit.

same problem with my k&N im up for sighning something and contacting K&N we should get a bunch of us with the problem to sighn somthing

This forum rocks... Just happened last night... Woke up -Got out of bed_skipped the comb and came straight to the Forum... Voila- The issue i wanted to research is on the front page Now a quick question...Is this covered under warranty? assuming it is a bad MAF. Same problem abs/psm failure

May or may not be relevant... I recall reading someplace "along the way" that K&N filters are over oiled from the factory. Suggestion was to wash and re-oil before initial use. Maybe this is contributing to the fouling / failure of the MAF sensor wires? No idea personally, just passing this on...

My feeling is, the filter itself, is unlikely the source of the problem. I've gone through this earlier before everyone took the jump into these modified intakes. The MAF relies on the flow being laminar in nature, meaning the flow is equal across the tube cross section as tha MAF only measures the flow at a couple of points and assumes the rest of the flow to be the same. The OE MAF and intake is a tuned and calibrated system. When you change the intake configuration you change the flow patterens (turbulant flow) into the MAF making them uneaqual. Lets say the maf is now seeing an incorrect low flow reading and thinks there is less air going in than actually is. It will then cut back fuel to compensate resulting in a lean condition and throwing a code. The same could happen in the opposite direction, or anyplace in between, with the MAF seeing a high flow situation and then adding fuel. It's my opinion that a lot of the claimed HP gains are a result of the incorrect MAF readings and adding fuel to make more HP, not better breathing. When you change the intake geometery there is no telling what the outcome might be. As I said before, procede at your own perrell. I've been using an oiled type filter in my car for 3 years with no problems.

I agree totally with RayGT3. A K&N (or any other oiled filter) is unlikely to 'blow' a MAF - if a little oil gets on it, then yes it can go out of calibration but it can be cleaned of with contact cleaner and the sensor should work properly again. This is not the experience people have been having with the K&N intakes. What is happening here iis the intake goes on, works OK for a while then on comes the CEL. Cleaning the MAF doesn't work. Put in a new one and it appears to work for a few miles then... another CEL. One or two people have reported cleaning to appear to work if they've disconnected their battery as well What' I believe is actually happening s this. The intake goes on. As RayGT3 states, the flow over the MAF is not laminar as there are no flow straighteners on the K&N as there are on the OEM MAF tube. The MAF takes several (hundred) miles to re-calibrate fully - only then does it throw a CEL. The CEL is due to the lambda (O2) sensors effectively 'telling' the DME that the MAF is out of calibration (it isn't, it's just measuring the non-laminar flow incorrectly). If the MAF is clean, then cleaning it changes nothing and the CEL stays on. If it was contaminated, cleaning it will cause it to re-calibrate, no CEL to start with then back it comes after several miles again. Removing the battery lead also causes a re-calibration, hence it looks like cleaning 'worked' if the battery lead was disconnected. A few miles later - hello CEL! Replacing the MAF causes another (several miles of) re-calibration, also after which the CEL comes on again. Annoying, isn't it!! The trick with CAIs is to choose one that doesn't eliminate the flow straighteners. Fabspeed (to give you one example) found this out and have amended their instructions for their airbox kit - they now tell you to teave the straighteners well alone for this very reason. Hope the explanation helps Ian W

Thanks again for lots more great input. Here is the latest on my adventures with this whole scenario, and it seems to match up perfectly with the last 2 posts. I had read PorscheDoc's reply on the Autobahn forum about trying to clean the MAF with some CRC QD electronics cleaner and possibly trying a non-oiled filter to see if it worked (with the thought that the oil was getting on the MAF and triggering a fault). Well I got my AEM dry filter yesterday and immediately installed it, after disconnecting the battery and cleaning the MAF once again. Put all back together and took it out for the test drive. Once again, it looked good for about 5 miles or so, then on another hard pull in 3rd past 5 grand, the 2 lights come on again. As you can imagine, this is getting really frustrating. I think we have enough exact same cases here to say it SURE looks like the K&N CAI is the culprit. I would definitely be interested in contacting them to see what they are going to do for all of us who have experienced this with their product that evidently did not go through enough quality assurance and testing. However, I am still interested in opening up the air into the engine since the MaxFlo mufflers allow a little better flow out of the engine (open it up on both ends as they always say for performance). Has anyone experienced this problem or a CEL problem with the EVO CAI kit??? That was the one I was going for originally and got convinced to go with the K&N, a decision I am really regretting now. Thanks again for all the helpful input and comments. Anyone just post if you have any success speaking to K&N about this.

Here's a suggestion, take a hole saw and cut some holes in the existing air box. And before you beat me up about hot air and all that, yes, you will get a bit more warm air into the box when putting around town but at high speed the difference in air inlet temp is negligable. I have never seen a comparison of inlet temps with holes and without. Anyone have a set of measured numbers or are we just guessing? I think the latter. This solution is priced right and will cause no ill effects code wise. I personally would like to have those numbers as a reference so anyone with a few thermocouples and some time, go for it (ambient, air box inlet and MAF inlet temps vs. speed/rpm) . And let us all know.

I think I've had it with this product. I'm not willing to pour in hundreds of dollars trying to remedy for somebody else's eror. We also need to take into account we might put our entire engine at risk. The product seems to be poorly designed and K&N should take responsibility.

Another thought, if you really want to make an improvement why not get rid of those anchor batteries you're dragging around. Install a dry cell (Odyssey) battery, easy install, and save a bunch of weight for about $100. You'll get more "real" performance from losing 20 lbs than you could ever get from a trick air box. Just a suggestion.

Well I got to desperation on this issue so I once again disconnected the battery and put the stock intake back on the car to see if I would get the two lights again. Sure enough, as soon as I got to the highway and opened it up on the on-ramp, at 5 grand the two lights come on bright and strong. I really wanted to put my head through a wall when I got home. I guess at this point I'm going to have to bite the bullet and take it to the dealer to find out what codes the mega-bucks Porsche reader spits out. If it needs a new MAF, I'll replace it myself, but I've tried so much at this point that I really don't want to risk spending another near $300 for a new MAF online somewhere only to see those two lights come back on again (either because it's something else or the Porsche "special" reader/resetter is needed to clear out the codes). I think I'm starting to see why I had two Porsches in the past and never did one single mod to them...

I told you several posts ago...your MAF is blown...no cleaning or resetting is going to fix it. You need a new one. Only after it has been replaced will you be able to troubleshoot (since you do not have the codes read).

Thanks, wross. I know, I saw your suggestion about the blown MAF, but my scenario wasn't the exact same as yours. I have yet to get a CEL after the PSM Off and ABS lights problem started. The CEL I got was what I had it at the independent shop for, and they said that code was that the bank 1 longterm was running too lean. It was a few hours later on the way home from the shop that I got above 5 grand and had the PSM/ABS lights come on. At this point I agree that it sounds like the MAF is bad and about to kick the bucket which I'm guessing is when the CEL comes on. I'm just not one to buy $200+ parts to troubleshoot without trying all the suggestions first, and it was suggested by several others that I clean the MAF first. I saw your post on the same issue where you got the CEL after these two lights. So you got this with the EVO intake as well? Do you still have the EVO installed? And if so, has the problem come back since replacing the MAF? I'm very interested in finding out because I had been considering the EVO intake, but if it causes the same problem, I'm certainly not going that route. Thanks again for all the help.

I thought this problem with the K&N CAI and MAF was due to people installing the MAF backwards?

I guess I'm not quite sure why everyone is so convinced it's not a wheel sensor. I had the exact same problem when I bought my car last year and it turned out to be a wheel sensor. When that was replaced, the problem went away. The symptoms sound exactly the same as yours. David

Typically you will through a CEL after the MAF goes (and you clear the codes), but it can take some time. I removed my EVO V-flow, replaced the MAF and no problems since (this includes a day at the track with some boost). I had the dry filter, but I also have other mods which may impact the V-flow (hybrid turbos, Intake Plenum and ported headers). I am not "ruling out" the wheel sensor...just been my experience this is typical of the MAF. Do you have the codes for when the wheel sensor failed? The ABS/PSM idiot lights don't really tell you much other than the DME is having trouble communicating with them. You need the codes.

Spoke to K&N. Here is the deal. We and they have sold over 90 units, we need to pinpoint this problem. K&N exact words to us is we cannot do it, K&N does. So...my K&N rep told me that if you are having issues with the product, so they can fix the situation, send out a replacement, fly someone to see your car, or whatever they have to do, please contact their customer service number - [phone removed]. K&N will document the problem, ask you some questions, then have the Engineer of the 63 series kit contact you directly to get the issue solved. I have personally only had Yves contact me with an issue, most other issues have been with wrong install. So please contact the CS Department so they can resolve the intake issue asap for you. If you still have questions, please contact me. Thanks!

A quick thought for sfirestine. I don't know what year your car is, but there was an issue on pre-facelift 996s that caused the PSM and ABS light to come on and had nothing whatsoever to do wuth the MAF or any other engine related sensors. This involved an intermittent contact inside the brake pedal switch - the one that sits just above the brake pedal inside the car and switches on the brake lights when you press the pedal. These things used to fail with great regularity but only cost about �15 (UK) to buy and take about 3 minutes to fit as a DIY. The reason this caused the PSM and ABS lights to come on is that both systems 'knew' the car was under braking by sensing whether this switch was operated or not. Broken switch = no PSM or ABS, hence the lights. I'm not saying this is necessarily what it is, but there is a fair possibility, especially if you're not getting a CEL and your engine performance isn't going off. Certainly it's worth checking - the easiest way is simply to see if your brake lights are working properly when the ABS/PSM lights are on.

Ian, Thanks for the input. Worth while considering. However, this syndrome seems to be happening on at least 5 cars (from looking at this post) which recently had their K&N kit installed. Too much of a coincidence...

My thoughts exactly. My brother and I did this install together. He has an '01 Cab and I have an '01 C4. On our cars, if you follow the K & N instructions, the MAF would be mounted backwards. We ended up drilling new holes on the piece that mounts the MAF so the MAF was turned in the right direction. Weird thing though, my brother didn't get an CEL, but I did. The CEL was the ONLY light on however and it was a solid yellow. We ended up cleaning the MAF and disconnecting the battery and after 200+ miles, the light has not returned. Hope that helps you guys out.

The K&N instructions misstating on how to mount the MAF? What is the best way to avoid this and put it on the correct way.

I just talekd to K&N customer service. They've had this complaint before. They told me that the negative connector to the battery needs to be disconnected for more than 2 hours in order for the system to totally lose its memory. I'll just disconnect it for the night and report back tomorrow.

Sounds good, Yves... keep us posted. On another development note, I got my AutoEnginuity code reader tonight and hooked it up. As I suspected, not one single trouble code is being reported, according to their software. Since the CEL is not on, just the PSM Off and ABS lights, I kinda knew this would happen. I tried K&N as well and am waiting for a call back from them. We'll see what Yves finds out with the longer battery disconnect, but I'm not holding my breath. Also, on the direction of the MAF, I know mine is pointed in the correct direction. The air is supposed to flow toward the opening on the one narrow end of the sensor. I double checked with how it fits in the stock airbox and it is facing the same way in there (opening toward the filter element) as in my K&N install, so that should not be causing the problem.

The autoEnginuity code reader may not read the codes...it is a good data logger, but not the best code reader...for that you should get the durametric software.

I'll say it again, if the ABS and PSM are on, probably nothing to do with the MAF, check your wheel and b rake sensors.

Check for a P0102 fault. P0102 is the same error you will get if the MAF is unplugged. This can also cause ABS and PSM lights to come on as the DME is not sensing the PSM data and combining it with the throttle position and mass air flow readings. Second possibility is a (intermittent) bad wheel sensor. A shop with a PST2 could test that for you.

Ok, hopefully this is the end of my thread and problem finally! After speaking with K&N, they told me they contacted a local Porsche dealer who specialized in the K&N products as well. They mentioned a few things that could be causing these 2 lights to come on, but that it might also be that my car had one of the faulty MAFs for that year. They said there was an updated MAF and I decided to give that a shot. The part number on my MAF was 99660612400 and the new one listed on the Autohaus Arizona website was 98660612501 (I'm guessing with the 986 it is a Boxster part but works on the 911). I got it and the new MAF does look just a tiny bit different from the one on my car. I re-installed the K&N, adding the one additional "L-Bracket" mentioned in the thread here. I also put my AEM dry filter on the end instead of the oiled K&N one, jut to be really safe. Well I just got back from "driving it like I stole it" for the past two hours and so far the lights have not come back on, and I have not gotten any CELs. I also am not hearing the rubbing noises I used to prior to adding the bracket when it would rub against the one pulley tensioner. I will keep you posted, but so far so good! I did many many hard pulls at WOT past 5 grand and not once did any of the lights come on. So far the powerband appears to have really evened out as well, so I hope this is the end of it because I seem to have gotten a pretty darn good setup now!

with the new style maf you should also get a reflash for the dme

There is no faulty MAF and K&N is talking out of there @ss. For MY02 the entry path (air sampling port) to the sensor element was angled 45 degrees (1st image), every other Bosch MAF made previously and the MAF used on the TT up until MY04 was straight (2nd image), it helps but oiled filters still cause it problems. And as mentioned above the DME needs to be reflashed (I only found a DME record for updating the Boxster with the newer MAF but nothing for the 996. I don't own a PiWiS so it could be located there) because the output voltage curve of the sensor is different for each sensor. A dry filter is the only way to be 100% safe. Good Luck!!! Nothing sucks more than buying crappy aftermarket parts that have have zero R&D behind them.

the update is specific to the 986 but we usualy update early 996s as well as there are updated maps for them

Sfirestine - Which size AEM dry filter did you get? Was it the shorter 5" length with a 3.25 inlet opening?

Hi wlee, no it is the 3.5" by 5" one. The part number is AEM 21-204DK. I was going to get it at AJUSA, but then I found it cheaper at this place closer to me and I had it in a day with only like $5.95 shipping charges. Highly recommend them: PTuning

I just went to the AEM site and their alpha index doesn't even list Porsche there....where did you get the cross index for that part number?.....or is this strictly by measurements?

http://www.aempower.com/product_intake.asp?subCatID=23 Scroll to the bottom - they are generic filters...not made specifically for any make/model car

Not that I want to keep this post alive; however, I just purchased a 2002 996 and while driving back from NJ to VA......of course, both the PSM and ABS lights come on. I took it to a local shop and they related they received an error code 4460, which they said I needed to replace my hyrolic unit (about $3K). Has anyone had a similiar error code or problem? Travis

NON-OEM FILTERS KILL MAFS. I HOPE YOU CAN AFFORD ANOTHER MAF. GET RID OF CRAPPY AFTERMARKET PARTS A dry filter is the only way to be 100% safE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!! Quote: Originally Posted by sfirestine I will keep you posted, but so far so good! Good Luck!!! Nothing sucks more than buying crappy aftermarket parts that have have zero R&D behind them

Well, hopefully my story will turn out like yours. I installed the cold air intake from K&N last night and have had the same issues some of you reported. Mine were a little different though. I started the car after following ALL of the instructions. Right from the get-go, my PSM off and my ABS lights came on. The car seemed to idle ok for about 30 seconds then my engine light came on the idle on the car turned to a little hesitation...if I gave it a little gas, the rpms would climb up fine but they would drop really low and the battery power would drop lower than 12 and it almost seemed the car wanted to die. I guess I will have to contact K&N to find out what story they will tell me know - well, I took my chances as I had read several nightmare posts about this product. I guess there was part of me that felt that maybe it was in issue with installation but, I guess I have to admit when I am wrong. I WAS WRONG. There - that feels better. Before I contact them I guess I will disconnect the negative terminal yet again for a couple of hours and see if that does anything....

you must of way way way over oiled the filter to throw faults that quick. sounds like you started the car with maf unplugged (shuttuing it off and plugging it in will not clear it) or the connection is loose or the maf is in backwards.