I wanted to erase my old iPhone 3gs, but it redirected me to this Restriction Passcode:
If you have a jailbroken iPhone, this is the method you follow:
1. Download and install iFile
2. Go to /var/mobile/Library/Preferences/
3. Locate the file named com.apple.springboard.plist and tap on it
4. Tap on Text Viewer
5. Search for ‘SBParentalControlsFailedAttempts’ (you can just type ‘FailedAttempts’ too)
6. You should see a <key> and a <string> for this field like this:
(the number within string might differ)
7. Just beneath this, type the following:
8. Quit everything.
9. Open Settings → General → Restrictions again and enter 1234 for the code.
Voila! You are in. Now change the code to something better/safer.