Code 151 means IRS is reviewing your return. There is nothing you need to do right now. IRS will send you a letter of explanation in approximately 4 weeks. The letter will provide details of the reason for the review and give instructions about what you need to do next. Sometimes it is just a matter of providing some additional information. The following FAQ will provide additional information for you.
https://ttlc.intuit.com/replies/6633192
