Display shows E2 and the Marey water heater shuts off shortly after ignition or during operation.

Safety first: Turn OFF power and close the water supply. Allow the unit to cool completely before touching internal components.

Steps to address overheating:

• Check outlet restrictions: Ensure the hot water shutoff valve is fully open. Remove and clean faucet aerators and showerheads that may be clogged with mineral deposits.
• Verify flow rate: Open a hot tap fully and confirm strong flow. If flow is weak, clean the cold inlet filter screen and check for partially closed valves.
• Descale the heat exchanger: If you have hard water and no softener, scale buildup is likely.
  • Isolate the heater using service valves (if installed).
  • Connect a small pump and hoses to circulate a descaling solution (such as white vinegar or a commercial descaler) through the heat exchanger for 45–60 minutes.
  • Flush thoroughly with clean water afterward.
• Inspect high-limit thermostat: With power OFF and cover removed, locate the high-limit thermostat/thermal cutoff on the heat exchanger. Some models have a manual reset button—press it if present. If the thermostat is physically damaged or repeatedly trips, replace it.
• Check temperature setting: Ensure the set temperature is not excessively high. Lowering the setpoint can reduce stress on the heat exchanger.

When to call a technician: If the E2 returns immediately after reset, or if you are not equipped to perform a proper descaling procedure.