Pad replacement and warning lights ?

[S.Speed]

Hi all,
I noticed the rear Pads are wearing pretty low..
Is there any advantage to replaceing them BEFORE the warning light comes on?
What I mean is, if the warning light comes on how do I reset it?
Does it auto reset when the new pads are in? Or do I have to have it reset by MB
If I change the pads early can I reuse the sensor wire that goes into the old pads?
On previous cars I have done without the sensor wire and there was never an issue as I always keep my eyes open to the condition of the pads.

The car is a 2003 C270 CDI
The car has done 40k and I cannot say if the pads have been done before but the rears are worn more than the fronts are..

Thanks in advance for any advice given.

 

[Xtractorfan]

Just bringing this to the top of the pile..I would fit new pad sensors not expensive, may even come with the new pads..nearly sure the warning is self setting, but some of the tech guys will be able to give u correct details...

 

[television]

No setting to do the light will just go out if it was on, once the new sensors were fitted