Uneven rear brake wear

[Funkyboy]

Just noticed my rear outer pad on my 14 plate E250 has totally worn away. Only fitted around 12k ago. Inner still ok other side of car also fine. What is the most likely issue? Do the rear pins slide?

Thanks

 

[Rotorhead500]

Sounds like a sticky caliper...

 

[bembo449]

will be obvious once stripped down , brakes dont have many components to fail on them