ABS and PSM Off lights came on

Yesterday I was driving my 2002 C2 and the ABS and PSM Off lights came on. At the time I was accelerating briskly up a hill. When I got home and turned the car off and check to see if there were any error codes. There wasn't and when I started my car, sure enough the lights were off. Is this a symptom of something? Has anyone had this happen where the lights come on and then go off on their own?

U need a scanner that can read the stored codes in the abs module. Most likely a wheel.speed sensor issue.

You�d be amazed at how often cels are triggered by a low charging battery or faulty coil. Check those out before you go down a rabbit hole

Ahhh. I just checked and my LAUNCH CR3008 Plus does not access ABS codes. Thanks for the reply.

On 996 Turbo the warning light trifecta : check engine, ABS, PSM usually means the MAF is no good.

A malfunctioning brake light switch will also cause the ABS and PSM lights to come on ( and store a Code for Brake Pressures ).. The Brake Light Switch "must" activate the Brake Lights "before" the pressure rises in the brake system, otherwise the system deems this a fault in the pressure system...

I don�t want to open another thread� I had a similar issue 2 days ago on my 996. I was driving on the highway when PSM and ABS lights went on. However car was running very well, as always. No dirty MAF sympthoms. Yesterday morning I planned to buy a new battery as first try, but before I did a test if lights were already on. I drove car for about 60 km and no light switched on and car was running better than ever. This morning I used car again. No lights and car was running smooth and fine. Battery charge near 14 volts. What it could happened? A false contact? Some dirty on the wheels? Or maybe car was parked at the sun for some hours in a very hot day and this could have made some effect on the battery?

@Johnnysband did u test the battery before u swapped it? Have u checked the charging system (alt) with a meter? If not u have/had no idea if u had an issue. While its possible that an battery/alt issue can be the problem, some simple diagnostics can confirm a fault before u fire the parts cannon at it. Usually it takes a running voltage below 10v before sensors have issues.....i would bet u have not fixed your issue but hopefully u have.

Quotes source post: 20184414

I didn�t test the battery because I didn�t swap it! I tried to use car yesterday and today and everything was fine. PSM/ABS lights didn�t switch on again. Voltage on the gauge is always between 13,5 and 14.

I have the same car (02 C2). Mine will occasionally do that as well. Shutting it off and restarting clears it. Happens a few times per year. Not often enough for me to try to track down but I like the thoughts above.

Quotes source post: 20184073

2004 C4S also having the same issue and not wanting to start another thread. Perhaps with all of our info in one place we help find solutions. My symptoms are slightly different than the other posters: ABS+PSM lights come on only when the car is idling (usually at a stoplight) The lights do not come back on after turning the car off and restarting, either immediately or after a delay (minutes to hours) Has happened 4-5 times over last several months Car running well, no issues with idle, power, etc. Cleaned the MAF anyway but issue has happened since then. Battery new this year and maintained on trickle charger (~14V after start, then ~13V after running some time). Conventional ODB-II scanner shows no codes. Durametric shows "4460 Pressure Sensor" fault. @Porschetech3 your comment seems relevant to my case. However, the lights come on when I'm idling at a light, after I've been holding the brake pedal for a while, not just when I press it. Is this consistent with your experience? It feels a little bit like the ECU fires off the lights when it is going through a diagnostic cycle (such as when it runs the SAI pump sometimes when idling). Is the correct switch to replace the one at the pedal ( 996-613-113-03-OEM )? It's pretty cheap, but I wonder what diagnostic exercise you might recommend before replacing it to confirm that is the issue. BTW, I haven't been in a good position when the lights are on to test the car and see if indeed the ABS and PSM systems are OFF. Does anyone know?

The 4460 pressure sensor is a sensor that is either on the ABS unit or on the PSM pump. I had this code and unplugging the sensor and replugging it a few times fixed it. Look for a 3 pin plug on a cylindrical sensor. Also if you have swapped to a 997 brake master this code is very common and the fix is to install a brake proportioning valve in the front brake pipe between the master and the ABS.

Quotes source post: 20184765

Yes, this is the exact Code/scenerio I see as the most common and also misdiagnosed ....I have seen many repace the ABS pump and or pressure sensor for this when it is the brake light switch... Carefully adjust the new brake light switch to activate the brake lights at the least touch.....

Quotes source posts: 20185058, 20185076

Fortunatey I have not swapped in the 997 brake master. My C4S is bone stock. Thanks guys, I'll do both: clean the contacts and reseat the pressure sensor plug and also replace and carefully adjust the brake light switch. I'll report back with results a few months after the work hopefully without any reoccurrence.

Bumping this up, I am having the ABS and PSM lights come on during driving. Not immediately, sometimes after an hour. They always clear on restart and may be days or weeks before they reappear. Car is at second home so I don’t have a trusty mechanic nearby. I took it to a place that does 911 work they said the only codes were low voltage. Battery was a few years old so I replaced it, came back on in 15 minutes from repair shop. The brakes are working fine. I can live with it but would love to find a solution. I’ve read a bit online but haven’t found exactly this issue. 2004 C2 MT

Quotes source post: 20422378

As it can be many simple things such as the brake switch or one of the four speed sensors in each wheel, it would be better if you can get the error from the obd port. Most probably it is the brake light switch, but just to be sure...

Any Dakar Rally driving ? I hit some pot holes headed from WV to NC in my C4s. Lost ABS/PSM. Had an alignment done at my Charlotte destination....Car returned to normal handling but the warning lights remained on. Indie shop did not have the proper gizmo. But the next day they went out on their own

My PSM and ABS lights started coming on, and Ive been told by my Porsche independent shop its the ABS pump. They will go off sometimes after I restart it, but they always come back. Ive been driving without ABS for a while now. 2000 manual C4 coupe with 161k miles

Quotes source post: 20423403

Is there a specific code number that will be thrown if the brake switch is the problem? Thanks.

Quotes source post: 20425258

Yes this is why you need a reader such as piwis, durametric or something that is Porsche specific, to get the full analysis.

I have the PIWIS 3, so that is why I was wondering if there was a specific code number to watch for in the results.

There is a code, I�ve seen it in the workshop manual while searching for ABS module testing. I�ll see if I can dig it up again

Quotes source post: 20426002

Just post all the results. It will be very apparent.

I don't recall a code specific to the brake light switch. On the turbo side this combo of lights often means the MAF has failed. Somehow PSM uses the MAF reading to estimate engine torque. When the estimate is blatently wrong PSM pops the PSM, ABS, and sometimes the Check Engine light.

Quotes source post: 20427008

Ι had a problem on the brake light switch. Intermittent. PIWIS showed a code and an explanation

Want to add to this thread. I started getting the PSM and ABS warning lights and the "Drive to Workshop" message intermittently about a year ago. At first, cycling the ignition off/on would clear it. But the problem became more persistent; almost everyday this year it would trigger, either on start up or while driving. The AGM battery was replaced under full warranty by NAPA thinking that the low voltage reading was the cause; didn't cure the problem, and I replaced the brake switch; also didn't resolve the issue. Eventually, a month ago while in stop and go traffic, the car went into limp mode and wouldn't accelerate past idle speed until I restarted it. I got home and plugged in the OBD scanner and the following codes came up: P2135, P0121, P0223. All related to Throttle/Pedal Circuit voltage issues. First thought was that I would need a new e-throttle assembly, then I remembered that Sprint Booster had been installed on the car by my dealer 15 years ago! I barely used it because the X51 throttle is already very reactive, so only on the occasional trackdays did I ever activate it. I hate to admit it, but I used AI to confirm the codes, symptoms and that the presence of the Sprint Booster as being the most likely culprit. Since I'm not as flexible as I might have been 15 years ago or am I training as a contortionist for the Cirque du Soleil, I stopped in at my dealer and they graciously removed the offender and cleared all codes with PIWIS at no charge. My tech, who I've known for years, admitted that he loathes these aftermarket devices since they can and do cause these "ghost" issues. My car has been problem free for a month now. And no hidden codes detected with my OBD scan tool.