Have replaced gas cap, and local shop replaced the vapor detection pump. Light stayed off for about 185 miles, but has returned. The shop stated that more time and
use must go by before light and code will re-set. This seem accurate? I'm trying to avoid going down the rabbit hole in search of the solution as there seems to be many different
potential repairs (and cost) to resolve this?

 

I see you don't have any replies yet, so I'll see if I can get things started.
Did the problem come about suddenly after some event?
Have you been smelling any fuel vapors about the time the code came about?
Any repairs on the fuel, or vaor recovery system just before the code came about?
Have all of the vapor recovery system lines & fittings been inspected & or put right?
If so, then it might be time to rig & perform a smoke test of the vapor recovery system.
Some beginning thoughts for consideration, let us know what you find.

 

Hi. Light appeared out of nowhere-car was and is running fine. Have had two smoke tests, replaced leak detection pump as well as new purge valve. Also have tried
two new gas caps; latest one purchased from a dealer. Light seems to go on within a week and 200 hundred miles of being re-set.

 

Sounds like you've put all of the usual suspects on your list & addressed them as expected.

One week / 200 miles to turn the CEL on again seems to be a really small leak & 2 smoke tests haven't found it. SO, it might require a "sniffer" be used, rather than a visual look for smoke/vapor.

Good idea to have opted for a OEM gas cap. Have a very close look / inspection of the gas cap fill tube Sealing surface. It needs to be baby butt smooth, no deep scratches, gouges, nicks, or dings where the cap seal contacts, so it makes a good solid tight seal. Also inspect the new gas cap seal while flexing it & looking for molding irregularities, like bumps, cuts, raised knit lines, air bubbles in the seal material..

If any of the vapor recovery plumbing has been disconnected, moved, removed, replaced, or repaired, or otherwise messed with in the past, even to be moved to get at something else during a repair, reinspect that area, hose, tubing, clamp for chips, cracks, divots in a hose from being mashed, or rubbed by improper routing, or signs of dry rot cracks in rubber parts.

 

Thanks. May do nothing at this point as a 15 year old vehicle (it's a 2005) in this state no longer needs to pass an emissions test. Lucked out and was able to get it inspected last week.