RSA OAEP Error Detection Probability
In OAEP we pad the message with $k_1$ zero bits and $k_2$ random bits. It's the zero bits which give you verification. The all or nothing gurantee means if you change anything you will flip all bits with probability 0.5 and the chances of getting $k_1$ zero bits by chance is 1 over $2^{k_1}$