Tesy digital water heater shows E03 and does not heat; sometimes relay clicks but no temperature rise.

Safety first: Isolate power at the main breaker. Confirm zero voltage at the heater’s terminal block with a multimeter before touching any internal wiring.

Steps:

• Access the element terminals: Remove the lower cover to expose the element flange and wiring. On Tesy models, the element is usually mounted on a flange with two or more terminals plus earth.
• Visual inspection: Look for burned connectors, melted insulation, or signs of overheating at the element and wiring.
• Check element continuity: Disconnect the wires from the heating element. Measure resistance across the element terminals. A typical 2 kW element will read around 25–30 Ω. If the meter shows OL (open circuit), the element is burned out.
• Check thermal fuse/thermal cut-out: Some Tesy flanges include a one-shot thermal fuse or resettable thermostat in series with the element. Test continuity across it. If open and not resettable, replace the assembly.
• Tighten or replace connectors: Clean any oxidized spade terminals and tighten screws. Replace any heat-damaged connectors.
• Replace the heating element if faulty: Drain the tank below the element level, remove the flange bolts, and pull out the old element. Install a new Tesy heating element assembly with a new gasket. Refill the tank fully before restoring power.
• Test: After refilling and bleeding air from hot taps, restore power and confirm that E03 clears and water heats.

Note: If the element tests good but E03 persists, the power relay or control board may be defective and should be checked by a technician.