Ariston electric water heater does not heat; display shows E01 and water remains cold.

Safety first: Turn OFF the water heater at the breaker or disconnect switch. Verify power is off with a multimeter before opening any covers.

• Access the element: Remove the front cover of the Ariston heater (usually held by screws). Locate the heating element flange and terminal block.
• Check manual reset thermostat: Many Ariston units have a red reset button on the safety thermostat. Press it firmly until it clicks. Restore power and test. If E01 clears and heating resumes, monitor for recurrence (could indicate overheating or limescale).
• Test the heating element: With power OFF and wires removed from the element terminals, measure resistance across the element with a multimeter. A typical 1500–3000 W element should read between ~15–40 Ω. If it reads open (OL) or very high resistance, the element is faulty.
• Inspect wiring: Check for burnt, loose, or discolored wires at the element and thermostat. Tighten loose screws and replace any heat-damaged conductors.
• Replace the element if needed: Shut off cold water supply and relieve tank pressure by opening a hot tap. Drain water below element level. Remove the element flange (usually 4–6 bolts or a threaded element). Clean the sealing surface and install a new OEM Ariston-compatible heating element with a new gasket. Refill, bleed air, then restore power.

If E01 persists after element and wiring checks, the control board may be misreading current and should be evaluated by a qualified technician.