Can I clean my vinyl fence with a pressure washer?
It's not a matter of whether, but how. You can cut through many materials with a pressure washer if you go about it like a samurai. I've cleaned soft vinyl boat furniture with one, and I've damaged similar materials when I got careless.

Approach the job carefully and with just enough pressure (controlled by distance and nozzle shape) to do the cleaning and you'll be fine. Experiment on a scrap if you have one available to see just what it takes to cause damage.