The work includes bridge joints and lighting maintenance, along with safety barrier inspections.
A closure of the eastbound carriageway will be required between 8pm on Saturday November 8 and 6am on Sunday November 9.
A westbound closure will then take place between 8pm on Saturday, November 15 and 6am on Sunday, November 16.
Chris Pope, Highways Agency project sponsor, said:
The Second Severn Crossing is a vital transport link between England and Wales, and this work will help keep it operating safely for many years to come.
We have planned the work carefully to cause the least possible disruption to road users and will also be taking the opportunity during the closures to carry out other work such as carriageway sweeping and central reserve grass cutting to reduce the need for traffic management in the future.
The work is being carried out over two weekends when traffic flows are lowest but road users are advised to plan ahead and allow longer for their journeys.
Road users will be advised by diversion signs to use the M48 Severn Bridge, adding 1 mile to the journey for those heading for Bristol, London and the Midlands and 9 miles for those heading for the South West.
Members of the public should contact the Highways Agency Information Line on 0300 123 5000.
Journalists should contact the Highways Agency press office on 0844 693 1448 and use the menu to speak to the most appropriate press officer.