I did that one time. It wasn't a pressure wash, just a back yard garden hose wash. Water got around the plugs, and the plugs shorted and cracked.

95 Contour Zetec, ATX (wrecked, sitting in the barn) 95 Mystique Zetec, MTX 2000 Taurus SEL 3.0L Duratec 1994 Crown Victoria LX 4.6 V8 1993 Chevy Silverado 4.3 V6