I recently purchased a 99 Carrera 4 and after a few days both the PSM and ABS light stayed lit on the dashboard. It illuminated after initial braking and stayed on until the engines was shut off then lit up again under braking when next driven. The past two days the lights do not come on and remain lit under braking. Does this mean that all sensors are operating as intended or do I need to have the Porsch evaluate?

 

Brake light switch symptoms. Easy replacement.