If i recieved a tax topic 151 with a reference #1242 and i know where the mistake was made can i amend my return

Absolutely! If you know where the error happened you should file an amended return to correct that issue. Amended returns do not “catch up” to your original return and replace them; they are processed as two separate returns.  

Amended returns have to be printed and filed by mail.  It can take the IRS up to 12 weeks or longer to process them.   If you are due a larger refund than on your original return, your amended return should only show the difference and you will receive a separate check for it.  If you owe money on your amended return, it will show only the new amount owed, you will have to mail a check with the return. You can check the status of your amended return by clicking here: https://www.irs.gov/filing/individuals/amended-returns-form-1040-x-/wheres-my-amended-return-1