pathfinder engine is fairly well covered.
i have literally bathed the engine with water numerous times with no problems.
3 important things to consider:
keep a pressured air hose ready (at the gas station) and air dry the electronics very well when done.
cover the air intake with a plastic bag
dont use any shampoo substances that may damage the hoses, and cause them to start cracking up in a few months. use recommended only.
oh and might wanna wait for the engine to cool a bit before spraying with water.