Turns out it wasn't anything to do with the water in the engine bay. When I was vacuuming the passenger footwell I bumped a wire tucked up under the dash and realised it was unplugged (as it should be) as this is where you hook up the software to the cars ecu, thinking I unplugged it I plugged it back in and tucked it back not thinking anything of it but as it happens the wires nut stay unconnected otherwise the computer throws the flashing MIL