Error code P0301 after pressure washing engine compartment. Can coil pack be damaged from the water?

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Apparently, the plastic cover that runs over the top of my engine, protecting the coils, is missing. So, when my bf pressure washed the engine compartment, water submerged the spark plug wire boots. Like I said in an earlier post, I drove it about 6 miles as it progressively began sputtering, hesitating, knocking and CEL began flashing. Parked it... and smelled rotten eggs. Read a code P0301. Bf checked the coils and wires and found everything submerged. #1 boot was not sealed as it should have been. Bf dried everything and sealed #1 boot to spark plug. Cleared the code, car ran fine. Later on, took the car to the store and all the symptoms, incl. flashing CEL, and rotten egg smell returned. Could it have damaged the coil pack?