Due to the location of the Engine ECU being directly under the Scuttle Panel, in due time the drains get blocked with dirt, leafs and Moss, which prevents water from draining correctly, and over multiple rain falls the area gets filled and the ECU gets submerged in water.
Prevention of Water
To Prevent your ECU from failing due to water ingress, regularly check the area is clean and drains are clear
A few modifications can be done to allow more water to escape easily to prevent the retentions and the ECU to be placed slightly higher to allow the sealed edges of the ECU to be slightly higher thus preventing the water to sweep in the ECU.
M6 Nuts placed on the 2 rear Studs to Raise the ECU slightly.
Wiring Harness raised to allow enough clearance underneath to allow leaves and debris not to obstruct rain water from easily flowing to the drain holes.
Ensure ECU Area is kept clean and clear to prevent your ECU from water ingress