PSM/ABS warnings - Need Help

I have a problem that started happening shortly after I purchased my 2003 Carrera 4S. I had the car about a week and decided to take a friend for a "ride" in my new toy. I took it up to about 100mph and then hit the brakes. I got an ABS and PSM failure warning light. When I turn the key off it resets. When I crank the car up and drive it the lights stays off for about 1/2 mile and then comes on. It may come on almost immediately upon starting driving, or it may go for miles. This is crazy. I have searched the internet and found a lot of potential causes, but no solution. I have installed a new MAF sensor Had the battery professionally tested - ok Had the alternator professionally tested - ok Cleaned all four wheel speed sensors Replaced the brake switch and verified that it is working correctly My car has been modified with a 3.8 liter cup engine, 20" wheels with the correct tire diameter. It also has a K&N filtercharger system. It has a complete Fabspeed exhaust system with no cats installed, so I am getting bank 1 &2 oxygen sensor codes. The ECU has been programmed by Fabspeed. The engine runs smooth as silk until the lights pop on, and then it seems that the car goes into a limp home mode... After this the engine loses power and does not run smooth. My code reader does not pick up any codes other than the Oxygen sensor codes so I took it to Hendrick Porsche in Charlotte. They suggested that it could have been due to the MAF sensor, but because of the other modifications they were not certain. Any ideas? Love the car but I am at wits end...

Searched the forums but couldn't find anything exact to my situation. 06 DB9 (3 pedal) 10k miles, newer battery. Drove car yesterday. Noticed when I went to start it, I had to press the start button twice. Thought I just didn't push it hard enough. Started no prob. Also started it again a few times that day. No probs. Decided to go for a drive tonight. Key in ignition...wait for system check...no faults or warnings...hit start button and nothing!!!! The light by the passenger footwell dims/turns off when starter button is pushed. All lights, radio, door window regulator, headlights and seats all work. Usually use Aston battery maintainer. Left it off for one day. Never hit bat disconnect. Checked push button over battery just in case. Replaced starter solenoid fuse (although it looked ok), checked starter button fuse (looks OK, didn't have one of those small fuses on hand). I'd say battery is good but haven't officially checked it. Visually checked wires by clutch switch. All looks OK there. Once system check is complete, the remaining lights on are: the oil pressure light (normal), and the steady yellow engine light (I think that's normal cause it isn't running yet). FYI The starter button lights up white, not red. Isn't it supposed to be red when starting is avail? 1. Bad starter button? 2. Bad battery??Enough battery juice to run accessories but ECU doesn't recognize it as enough to activate starter? 3. Bad starter? 4. Bad clutch switch? Any other ideas? Never had a low battery warning. Thanks in advance

ABS/PSM would indicate a brake problem. Take it to a Auto Zone or someplace that can read the codes. I would think to also check the brake pads and roters, this could be an indication they need to be changed. Also, this indicates your ABS is not working correctly so under braking there will be possibly no adjustments to the wheels, this is most likely why you go into limp home mode.

Bad or disconnected clutch switch would be my guess.

I had same problem. Replaced brake light switch with new OEM. Problem solved.

Hi all Forgot to post what the dealer found regarding my inop start button. After a few hours of searching, the technician found a broken wire on one of the clutch pedal "plunger" type switches. The broken wire was covered by a sleeve. The way the wires for that switch were mounted caused the wire bundle to be pressed up against the firewall every time the pedal was pushed. Bad design! Since sticks are relatively rare, I guess that's why this hasn't sparked a service bulletin.

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Quote: I have ordered one, and will pick it up in the morning. I'll post up my results. Thanks.

Same thing happened to my 05 DB9. I rerouted the wires a little bit as it seemed like the action of depressing and releasing the clutch pedal caused the wires to fray and connection to loosen over time. No problem at all since I fixed it though..

This morning I installed a new, genuine Porsche, brake switch. No change. The PSM / ABS lights come on as soon as I hit about 14 -16MPH. I am thinking about buying a wheel speed sensor and swapping it into each corner followed by a test ride. Maybe one of them will be bad. Is this a good idea? Any other suggestions? Thanks

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Quote: OK, here is my take. First off, if the cat bypass pipes were installed thinking through to the logical conclusion the Fabspeed 90 Degree 02 Spacers would have also been installed which would eliminate the CEL as you are getting. Suggestion, have them installed, $150 for the set. Take it to an indy or the dealer, you have a problem with your breaking system, possibly bad fluid, pads and roters need replacement. Don't mess with this. Just so you know, the break pads and roters are designed to be replace at the same time, you should not replace one or the other, which I suspect may be the case here. Jim

Your best chance is to hook it up to a Durametric (or similiar) tool. I have the same problem, and have been doing research on the problem for a while. Replaced the brake switch and nothing. Cleaned all the sensors, and nothing. I'm hoping that the durametric will tell me which sensor is messed up, because I heard that the wheel sensor wires sometimes break or lose connection which causes the lights…I'll try to get under the car this week and let you know.

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Quote: My new wheel speed sensor will arrive tomorrow. I'll swap it into each corner starting at the right front, and post up what I find. Good luck with yours...

I swapped the wheel speed sensor into each corner. No change... It seems that when the engine is cold it runs rough and the PSM/ABS lights come on almost immediately upon starting to drive. After the engine comes up to temperature it may go several miles before the warning lights start going off. I'm starting to buy into the idea that the problem is with something besides the actual ABS or PSM systems. I'm getting desperate. Any other ideas?

1. Get Durametric, read codes and post them here. It's cost is peanuts compared to time you spend wondering your problems and finding shops with inferior one-cable-fits-all OBD readers. ( My guess is P5525 , Torque transmission from the DME disturbed at times ...) 2. Before that replace that K&N with OEM airfilter. Only problem with this is that after the change you should get all previous codes cleared...depending of the origin just removing the cause (or disconnecting the battery) doesn't remove the CEL. Use MAF clener before starting the car again. 3. Are you definitely sure that the Motronic really has correct programming for removed cats, ie it ignores secondary O2 sensors?? Or for that 3.8l Cup engine ..which Motronic does your car have? OEM 4S or something else? Programmed by whom? One, but quite far fetched possibility is that your rate-of-turn sensor has gone bad. ( P4420 , Rate-of-turn sensor ) For detecting that you need Durametric or OEM Porsche workshop equipment (=PIWIS). Remember that when you have ABS/PSM on you really do not have those electronic aids at all...they're totally disconnected.

I was going to order a durametric but the problem is that I am a Mac user. I will have to borrow a PC to be able to run the durametric. Any other options out there for a Mac?

Finally got the Durametric and have the following codes: 5525 Incorrect Data Transfer DME Master Control Unit 4440 Steering Angle Sensor I have preformed the steering sensor calibration procedure per the instructions. No change. Is there any way to test the actual steering angle sensor? Where is it located and what does it look like? Any ideas of the next step?

Removed the K&N air filter assembly and installed an European GT3 airbox. The 5525 code has disappeared, but I am still getting the 4440 Code and the ABS/PSM warning still comes on. What is involved with changing the steering angle sensor?

Sorry for your problems but thats what you risk when you buy an over modded or radically altered 911.. They may look very cool but 'Mess too much with them and they will mess right back at you'. The PO had his fun over modding and now you pay the price. Hey thats OIMHO but it needed to be said to protect other prospective 996 buyers who are reading these pages. Run away from a modded up car in preferance to a stock 996 and again thats OIMHO... 20inch wheels???? 3.8ltr engine?????? God Almighty.. thats enough.....that says it all....

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Quote: The 20" wheel/tire combination that is on the car has the same diameter as stock. What is the problem with this? The 3.8L engine is a Porsche crate engine. Yes the car is modified, but I am getting the same codes as many non-modified 911's that have posted up with the same problem. I am a first time Porsche owner that is asking for help. You are apparently an angry old man that has nothing better to do than run your mouth. If it is so important that you inform potential buyers about the horrors of buying modified vehicles, then make your own thread.

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Quote: Whoops... A little touchy arn't we haha.

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Quote: Steering angle sensor is located on -actually around- your steering column, to replace it your steering column must be removed. They might go bad, as all electronic devices. You've tried already to do the calibration, but do you know is your steering correctly aligned...wheels straight with steering rack centered and steering wheel straight?

The problem is solved. It turns out that the problem was a bad MAF sensor which was caused by using an over oiled K&N air filter. The actual cause of the problem was hard to identify because I had installed the MAF almost as soon as the troubles began, and the code instantly came back. As a result, I dismissed the MAF as the problem. When I actually figured everything out, I was watching the Durametric when the ABS light on the dash illuminated, and saw the MAF code turn on at the same time. This caused me to dig deeper into what would cause an instant failure of the MAF. I cleaned the MAF sensor and guessed that the cause was the filter oil so I just removed the actual filter and drove the car without it. No problem. I then put the filter back on, and almost instantly got a MAF code. I then cleaned the sensor one more time, and installed the GT3 air intake, and no more problems. I probably could have just washed the K&N and lightly oiled it and everything would have been ok, but I didn't want to risk a future repeat... Thanks to everyone for their suggestions and helpful information.

I bought a 2001 996 C2 with K&N filter, sports exhaust but otherwise unmodified. It has the PSM / ABS / Airbag lights all on, plus the fuel gauge is not working and the front trunk release mechanism clicks but will usually will not pop open. I scanned the codes with my Durametric and get the following: Bosch Digital Motor Electronics Motronic 7.2 Current Fault Codes P1571: Porsche fault code 39 Immobilizer ABS/PSM 5.3 Module Identification Part Number 520.996.618.15 Supplier Part Number Current Fault Codes Airbag B05 Current Fault Codes 49: Belt buckle, passenger 3: Supply voltage Automatic Air Conditioning H01 Current Fault Codes 31: Fresh air blower fault Does this look like an ABS sensor, passenger belt buckle wiring and fuel sender unit are all bad? Anything I can check before I throw a load of parts at it?

So what do you think the 4440 code was all about?

First time post here. I have a new to me 996 4S cabrio with the PCCB and X51 packages and have just started getting the dreaded PSM/ABS Light. I get a momentary stutter at speed and then within about 2 miles the PSM/ABS light comes on and flashes and then goes solid. I also have intermittent CEL's like P1133 and P1126 that usually show up just after this ABS fault. It just happened again today and there is a new code I have to pull later when I get home. Braking is normal when this happens. I turn the car off, turn back on again and it's gone for awhile. I searched this forum and found notes about the brake switch so I got a new one and crawled under the dash and replaced it. I hope I never have to do that one again.... head down, feet up in the air over the front seat and it took forever. Saw a post about putting a little grease on the feet on that switch to help twist in place. I'm not sure I've ever cursed as much doing that R&R. PSM/ABS light lit up again. More research. Found it could be a bad MAF --- so I tried cleaning it first. After about a 1/2 hour of driving at highway speeds PSM/ABS light on again. Other codes were the 1126 and 1133 again. So I replaced the MAF a second time now and thought that would take care of the PSM/ABS thing -- well it didn't. Car felt and ran amazing again for about 1 hour... then I felt that little hesitation and sure enough - Light is on again. I bought the car at 45k and it had some misfire codes and some other DTC mentions in the code. I sorted most of those with the parts I'll list in a second.The PSM/ABS light didn't start appearing until recently. Here's what's been replaced on the car: Coils and plugs (new version of coils) Air Filter - Standard Porsche Filter Oil Changed to Mobile 1 as I had no idea what was in the car. Blackstone Labs said they saw no issues in the lab test they ran for me. Pre-Cat O2 Sensors MAF (Bosch) -- twice Brake switch Cleaned the ABS Wheel sensors. They were pretty mucked up with stuff. Verified there is brake fluid at the correct level Fister Exhaust Hack I'm going to pull the new CEL code that just fired up again but my guess is it will be the 1126 and 1133 codes. I'm also going to try the one idea I saw about disconnecting the MAF and see what happens. The one thing I'm not sure about is how to test the wheel sensors and/or test the MAF itself. I'm at a bit of loss for ideas here. I'm about to pony up $ to take it to my local dealership but I hate admitting defeat. I also have another older sportscar that lacks all of the electronic gadgets the 996 does but I've done most of the work and restoration on her including some strange ignition and electrical issues so I'm not a novice but honestly I'm stumped here. Checking with a friend to see if they have a Durametric and/or maybe buy one. HELP!!!!! What am I missing? Sorry for the long post but wanted to get as much detail as possible. Thanks in Advance. David Update: pulled codes p0430.. cats sounded good when I tapped on them installing the precat o2 sensors. Will see if it comes back. Also able to get the PSM/ABS light to come on if I pull the plug on the MAF. Immediate light. Scanner showed the MAF at .78 lb/m. at idle. Some posts I've seen indicate it should be a higher value. Could this new MAF be faulty?

There is a switch on the ABS unit that can be replaced. I don't have the part number and I am not sure you can buy them separately, but I bought a replacement ABS unit on ebay and that fixed the issue for me. Incidentally, on another car that I had the same symptoms, I replaced the brake light switch, which did not clear up the problem. Pulled codes for brake light switch again, so I tested the new switch, which was bad. Another new switch also was bad. The 4th switch worked and permanently fixed the problem.

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Quote: Thanks for the reply. I also just cleaned the throttle body as well. It wasn't too bad that appeared to block the movement, but cleaned it up so it's nice and shiny again. I'm not sure it's the switch as I still feel the slight stutter when accelerating and then within the 2-3 mile range the PSM light engages. I'm going to try disconnecting the MAF and run it and see how the performance is without it connected. Maybe it's also a brake sensor acting up. I'm still trying to find a local buddy who has a durametic as maybe that will show me more codes than I'm seeing and might direct me better. I'm also wondering if there is a small vacuum leak somewhere as well. Looking for someone with a smoke unit. Anyone have other ideas as well? I'm going to pull that brake switch again as well just to check it out.