An E5 error number indicates that your fan or venting is malfunctioning. You would probably have a clog in your venting if your fan turns on but then gives you an E5. Because the 45H versions vent straight out the front of the heaters, this only applies to the 45HI. Check the inside of your vent pipe for any dirt which might be blocking the airflow.

If your fan does not turn on, there is a problem with the voltage or something is preventing the fan from spinning freely. Unplugging the water heater from its electrical supply is a popular treatment for this. Then remove the 4 bolts which keep the lid in position to release it. Please take care not to harm this wire. You’ll need to unplug it from the display’s black connector, which is 6 inches away. On the bottom, the left edge of the hot water heater, there is a grey box that holds the computer board.

The computer board will slide out of the box freely if the two screws on the face of the board, at the bottom two corners, are removed. Next, check that all of the wires attached to the computer board are properly seated by disconnecting and reconnecting them. Finally, two blue rubber boots can be found on the computer board. Pull the rubber boot off the fuse nearest to the center of the board and inspect it for damage. Replace the fuse if it is not complete. Finally, replace the board, reinstall the cover, connect the water heater to its source of power, and check to see if the problem has been rectified.