If your Mac is reporting mysterious numbered errors, and you’re not entirely sure what the problem is, one good option is to use Check Computer. Running Check Computer will queue up the full suite of Techtool Pro’s tests, systematically checking the various components components in your Mac, looking for potential problems. At the conclusion of the test, a report will display the results, giving you a good idea about what what the next steps might be.
Surface Scan – track down i/o errors
If you’re seeing i/o errors, one possibility is that a drive has developed bad blocks (or sectors). Bad blocks are physically damaged portions of your disk that the drive can no longer avoid writing to. Writing data to damaged blocks can result in a variety of problems including slowness and data corruption. In most cases, finding bad blocks means it’s time to replace the drive.
Check Computer – Starting point for problem solving
For other errors, try Check Computer to do a complete test of your Mac. Choose the Tests icon, and then choose Check Computer, if it isn’t already selected. Click Run Check Computer. While the complete suite of tests can take a while, it will be the most complete set of tests you can run outside of an Apple Store.
Check Computer – Testing in Progress
Once the problem has been found, proceed with repair
The most common problem to arise when using your Mac is hard drive corruption. If this is the problem, you’ll find it with the Volume Structures test. If the Volume Structures test finds a problem with your disk, you can use the Volume Rebuild tool to repair it. If some other hardware component is failing, a physical repair may be necessary. For this type of problem, you may need to replace the failed part, or take your Mac to an Apple store or an Apple-certified repair provider.
For more information about using Techtool Pro’s tests and tools: