The pedestrian, who is aged in her 30s, was in collision with a red Ford Galaxy at about 9.30pm last night, Wednesday 3 February.
Police are appealing for witnesses who saw what happened, particularly any driver who may have stopped to help but left before police arrived.
The collision happened near the junction with Broadmayne.
Contact Police quoting incident 1170 of 3 February.
You can submit a report online at https://www.essex.police.uk or use the ‘Live Chat’ button to speak to an online operator between 7am-11pm.
Alternatively, you can call 101.