A Maxis PUK (Personal Unblocking Key) code is a secondary security code used to unlock a Maxis SIM card after the PIN (Personal Identification Number) has been entered incorrectly too many times, typically three incorrect attempts.

The Maxis ​PUK code​ is an 8-digit number that is usually provided by the mobile network operator when you first purchase the SIM card. It acts as a safeguard to prevent unauthorized access to the Maxis ​SIM in case the PIN is entered incorrectly multiple times.

If the incorrect PIN is entered too many times, the Maxis ​SIM card will become locked or blocked. At this point, the only way to regain access and unblock the SIM is by entering the correct PUK code. Upon entering the valid Maxis ​PUK, you can then reset the PIN to a new code of your choice.

So in essence, the Maxis PUK code is a secondary, device-specific master key that allows you to unlock and reset access to a locked Maxis SIM card when the primary PIN has been compromised or incorrectly entered too many times.