e39 speedo,abs,asc

Welcome to the forum

The ASC system would have been working overtime in the snow.  I have heard of a number of manufacturers cars who throw up traction control/ABS system failures after slipping in the snow then reset back to normal once the traction improves next time the car is driven.

Each wheel on the E39 5 Series has a wheel sensor which detects the speed of each wheel as it rotates.  These sensors are used as inputs for ASC, ABS, speedo, trip computer, automatic transmission.

The E39 is prone to wheel sensor failures but they can sometimes throw the odd warning off then are fine after leaving the car for a few hours or overnight. 

If the fault light stays on persistantly then you more than likely have a failed sensor.  You do need to get a diagnostic check done to confirm which one of the sensors is faulty.  This costs 1 hours labour, it's a standard thing.

A new wheel sensor is about £60 from Eurocar Parts and can be fitted yourself if you are handy with a spanner.  I replaced both the front sensors on my E39.  Takes about 30 mins, you need to remove the road wheel, a 5 mm Allen key for the sensor bolts and the sensor unplugs from the wiring loom within the wheel arch.  Reffiting is reversal of removal except you swear in different places.  You don't need to reset the diagnostic system on refitting as the system recognises the new signal and resets.

Keep us posted on the outcome.

Andrew