The project involves improving 3.4 miles (5.5km) of road surface in both directions by the village of Wix. The overnight work will begin on 17 August and last two weeks.
The work will be carried out during the week between 10pm and 4am until 28 August.
Highways England project manager Jennie Fraser said:
This vital resurfacing work will not only improve safety but will provide road users with a better driving experience. The white lines will also be more visible, improving driver safety.
We understand this work will cause some disruption for drivers and that is why we are carrying out the work overnight during the week to minimise the impact.
We have worked with Essex County Council and Essex Police on the diversion and will be using a split diversion route to try to avoid lorries passing one another. We have also lifted the weight restriction at Mistley during the work.
While the road is being resurfaced, both eastbound and westbound carriageways will be closed between B1035 roundabout (Horsley Cross) and B1352 roundabout (Ramsey), but local residents who require access will be escorted past the roadworks.
Eastbound traffic will be diverted onto the B1035 Clacton Road, right onto the B1352 New Road, right onto the B1352 Harwich Road to Ramsey to re-join the A120.
Westbound traffic will be diverted onto the B1352 Church Hill, at the roundabout take the second exit onto Oakley Road, continue on the B1414 into Thorpe-le-Soken, at the roundabout take the second exit onto B1033 High Street, turn right onto B1035 Tendring Road and continue to Horsley Cross to re-join the A120.
Members of the public should contact the Highways England customer contact centre on 0300 123 5000.
Journalists should contact the Highways England press office on 0844 693 1448 and use the menu to speak to the most appropriate press officer.