Tesy water heater shows E08; unit may not power up fully or may reset intermittently.

Safety first: Turn off the breaker. Confirm that the heater is on a dedicated circuit with correct voltage as per the rating plate.

Steps:

• Check mains supply: Measure voltage at the heater’s input terminals (by a qualified person). Ensure it matches the specified 220–240 V (or local standard) and is stable.
• Inspect terminal block: With power OFF, tighten all screws on the mains terminal block. Look for discoloration or melting indicating overheating.
• Inspect internal power supply: Remove the cover and examine the control board’s power supply section (near where mains enters). Look for swollen capacitors, burnt resistors, or cracked solder joints.
• Line filter check: Some Tesy models have a separate EMI/line filter module. Inspect for burning or cracking and replace if damaged.
• Replace control board if needed: If the internal low-voltage supply is unstable or dead, replace the electronic control board. Board-level repair is not recommended for non-specialists.

Note: Persistent low mains voltage from the grid should be corrected by an electrician or utility provider; the heater should not be operated outside its rated voltage range.