The incident occurred at Rawcliffe Bar Park and Ride at about 6.50pm on Monday 18 July 2011.
According to witnesses, the woman officers need to trace yelled out for help after apparently being approached by a man on a bicycle as she returned to her blue Vauxhall Astra car after getting off a bus.
The suspect was then seen making off on the bicycle.
It remains unclear what actually occurred in the incident as the woman has not reported the matter to the police.
Nevertheless, extensive enquiries have been ongoing to trace the victim and identify the possible offender.
Officers and PCSOs have also been patrolling the area to provide extra reassurance and safety for members of the public while the investigation continues.
The woman in question, or anyone who may know her, is asked to contact York CID as soon as possible on 0845 60 60 24 7, quoting reference number 12110119868.
Witnesses or anyone who can help to identify the unknown man on a bicycle are also urged to contact detectives.
If you would prefer to remain anonymous, please pass information to the independent charity Crimestoppers on 0800 555 111.
Rawcliffe Bar Park and Ride is situated approximately 2.5 miles north-west of York, at the junction of the A1237 and the A19 York to Thirsk road.