2001 986S throwing 4660 ABS/PSM error message

[John Orrell]

This car is primarily an Autocross P03 class car that is street legal. The problem I am having is that towards the end of a 6 run day, I get the ABS/PSM lights and a 4660 code on the reader. If I reset it right after it shows up, it comes back as soon as I start the car. If I let the car sit for a few hours, and reset the 4660 code all is good until the brakes are thrashed again. My suspicion is the ABS pump assembly, any thoughts?

[JFP in PA]

That code is for the pressure sensor in the ABS system; could be the sensor itself, but considering when it happens on your car, you could be boiling the brake fluid.  Have you checked the moisture level in the system?  If it isn’t that, most likely it is the system pump, but I would eliminate all possibles first as the pump is pricey.😣

[John Orrell]

Perfect solution. 4+% water in the BF. The BF I used came from six year old unopened plastic bottles that I had bought a case of. I opened a fresh one and it was at 3+%. Then went to the store, bought a fresh bottle and it read less than 1%. So I guess long term storage in sealed plastic bottles for BF isn't such a good idea!

[JFP in PA]

1 hour ago, John Orrell said:

Perfect solution. 4+% water in the BF. The BF I used came from six year old unopened plastic bottles that I had bought a case of. I opened a fresh one and it was at 3+%. Then went to the store, bought a fresh bottle and it read less than 1%. So I guess long term storage in sealed plastic bottles for BF isn't such a good idea!

 

Brake fluids have a defined shelf life, usually around two years in unopened metal containers, but I have no data on plastic.  This is exactly why it is always a good idea to own a brake fluid moisture tool, which is cheap insurance.  😉