Display shows E3 and unit shuts down shortly after ignition or element activation

Safety first: Turn off power and, for gas models, close the gas shutoff valve. Allow the heater to cool completely before resetting any high-limit devices.

Steps to check:

• Remove the access panel and locate the high-limit thermostat or overheat cutoff on the tank or heat exchanger. Many CTC units use a manual reset button on the high-limit.
• Press the reset button firmly until you feel a click. If it immediately trips again on the next heat cycle, do not continue resetting without finding the cause.
• Inspect for restricted water flow: check inlet filter screens, isolation valves, and any mixing valves for partial closure or blockage.
• For electric models, inspect heating elements for heavy scale buildup that can cause localized overheating. For gas models, check for blocked flue passages or a heavily scaled heat exchanger (professional descaling may be required).
• If the high-limit thermostat will not reset or shows no continuity when cool, replace the high-limit thermostat.

Warning: Persistent overheat conditions can damage the tank or heat exchanger. If you cannot identify the cause, contact a qualified CTC technician.