Macbook Pro 2014 shuts down at random intervals Thanks @fbara for suggestion to add more details

Device: MacBook Pro (Retina, 15-inch, Mid 2014)

OS: 10.11.6 (15G1004)

pmset -g log from one of the times it occurred


  UUID: (null) 2016-09-07 20:15:11 -0700 Start                  powerd
  process is started 2016-09-07 20:15:11 -0700
    Summary- [System: No Assertions] Using Batt(Charge: 81) 2016-09-07
  20:15:11 -0700 Assertions             Kernel Idle sleep preventers:
  IODisplayWrangler 2016-09-07 20:15:43 -0700 Assertions            PID
  104(hidd) Created UserIsActive
  "com.apple.iohideventsystem.queue.tickle" 00:00:00  id:0x0x9000001f5
  [System: PrevIdle DeclUser kDisp] 2016-09-07 20:16:52 -0700 Assertions
    PID 261(Google Chrome) Created NoDisplaySleepAssertion "Playing
  video" 00:00:00  id:0x0x500000223 [System: PrevIdle PrevDisp DeclUser
  kDisp]
Please make sure you also check your Macbook for excessive dust inside! 

I have a Macbook pro which shutdown randomly (and gave the shutdown cause -128 error, and also the reference code PPT004 - the battery requires service). When I cleaned the build up dust it started functioning normally again!

I just removed the backplate and used a can of compressed air to clean it. Check https://www.ifixit.com/Device/Mac_Laptop to see how you can remove the backplate of your model.

PS: Try not to touch any parts inside, because of static discharge