2020 X5 xDrive 40i M Sport--rear brake caliper question!

[greg328]

Need help, guys!

2020 BMW X5 xDrive 40i M Sport--doing the rear brakes--I bought the Bimmerlink app and OBDLink Cx--app connects to car just fine--but the brake service command does NOT retract the rear brake caliper piston.

So--I tried turning it gently with large pliers--careful to not damage the rubber boot--and the piston will turn, but is not retracting.

So, I ordered a brake caliper piston tool with the correct 3-pin head, it's on the way from Amazon--but I'm concerned the the piston is not retreating as I turn it.

Is there a point of no return with the rear caliper piston that once beyond it will not thread and retract? It's not so far out that it's loose but it's about 1/8" further in than it was when removed--my previous brake pads were very thin and worn.

Or do I just need the correct tool that will put pressure on the piston as I turn it, and cause it to retract?

Still puzzled why the Bimmer Link command did not turn retract the piston--I can hear the motor turning and the app indicates "brake service mode complete"--but piston has not moved.

Any advice most welcome at this time--X5 is down and cannot be driven until this problem is corrected.

Many thanks,
Greg
Austin TX