I've been experiencing issues with my old MacBook Pro, early 2011, A1297.

  1. It started showing some vertical stripes, but resetting the PRAM did help.
  2. Some time later it ran into RAM issues, but removing one of the modules resolved this.
  3. And now Apple Hardware Test has detected an error 4SNS/1/40000000:VDOR-18.507

error 4SNS/1/40000000:VDOR-18.507

In addition to the error, the MBP feels hot and I can barely hear the fan. I think they should run much faster. I am guessing it is some temperature or fan sensor.

I tried to ask on Apple's official forum, but it displays Access Denied, so I gave it up.

How can I fix the issue?

1 Answer 1


It is definitely either a sensor error and/or hardware problem that is triggering the sensor.

In a situation such as this you really need to take it to an Apple Store or authorised service repairer. If you have a Genius Bar near you, make an appointment there as they won't charge you for just a diagnosis.

Reset the SMC

Here are the steps for resetting the SMC on your particular MacBook Pro. This may help in terms of your fans and the Heat.

  1. Shut down your computer
  2. Keep the MagSafe adapter (power cable) plugged in.
  3. Press at the same time shiftoptioncontrol (on the left side of the keyboard) and the power button
  4. Let go
  5. Turn your computer back on with the power button.
  • It was a company laptop, they just gifted it to me. Will it work?
    – zoonman
    Commented Mar 18, 2017 at 1:59
  • 1
    Well, that really depends on what the root cause of the problem is. There's no way for me (or anyone here) to give you a definite answer. However, you could reset the SMC to see if that makes any difference to the fans and/or heat. I've updated my answer with the steps for doing this.
    – Monomeeth
    Commented Mar 18, 2017 at 2:09
  • I tried to reset SMC and PRAM. It didn't help. Thank you for updating the question. English is not my native language and I'm not good at it. I truly appreciate your help. It is all sounds like some hardware fault. I'm handy man, I used to fix some simple devices like radio. But MacBook is far more advanced and there is no schematic and I don't have much equipment to walk over the board and see all signals. Anyway it is all proprietary.
    – zoonman
    Commented Mar 18, 2017 at 2:46

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