2004 996 ABS/PSM issue

[Jbizzle78]

I have a 2004 C2 and the ABS/PSM light came on the other day. It happened after I did a full brake job. I thought it was one of the ABS sensors, but when I took it to a shop, the diagnostic computer could not read the ABS unit. The shop did a manual brake test the ABS worked but my PSM button on the dash no longer works.

Any suggestions

[jwetering]

This is happening to me as we speak, and also after a brake job. I've got a couple of threads in play.

This is what I learned

1) The switch at the brake pedal is known to fail which causes the ABS and PSM to shut down and throw errors. An obvious sign of a switch failure is if the brake lights don't work, but it can fail in other ways as well. It's easy to find and remove. A quarter turn and it comes right out.

2) If the MAF sensor is dirty or flaky it will cause the ABS and PSM to shut down as well. It's not clear why but it's been documented. In this case cleaning it will work but they are easy and cheap to replace.

In my case my brake switch tested good and I cleaned my MAF and I'm waiting to see if the fault returns. If it does I'm going to scan the codes and fix (replace) whatever the scanner tells me is wrong.