I tried replacing my rear brakes today and had issues returning the piston. I have the tool to turn it back in and turned it clockwise about 5-6 turns while pushing in on it. It didnt collapse at all. I turned it another few turns and it tightened a bit.... still not collapsing at all. I had to put it back together and leave the old pads on it.
Anyone have ideas on whats wrong and how to fix it? The dealer wants $999 to do rear brakes with rotors but i can easily do myself if i can collapse the piston.
I just completed a front and rear brake change on my 2016 L494 RRS. I put the car in e-brake service mode first so I can’t answer whether you can complete or not without setting this mode. I think not. One side I had to turn back and compress the other side compressed easily. FYI- I came across the e-brake service mode purely by accident as there is little info on DIY fir this model. Good luck.