Bosch E27 — Low voltage fault — power supply below operating threshold

What E27 means on your Bosch dishwasher

Error code E27 indicates that the control board has detected a voltage supply below the minimum operating threshold. Bosch dishwashers require 110–120V AC to operate correctly. When voltage drops significantly — due to a weak circuit, loose wiring, or utility brownout — the board triggers E27 to protect sensitive electronics and prevent components like the heater and motor from running at reduced power, which could damage them.

Symptoms

• E27 appears during high-draw phases of the cycle (heating, pump startup)
• The dishwasher may work normally at some times of day but fail during peak usage hours
• Control panel lights may dim or flicker before the error appears
• Other appliances on the same circuit may also show issues

Common causes

• Overloaded circuit — the dishwasher shares a circuit with other high-draw appliances, causing voltage drop when multiple devices run simultaneously
• Loose outlet wiring — corroded or loose wire connections at the outlet or junction box create resistance that drops voltage under load
• Long wire run — if the dishwasher is far from the breaker panel, thin-gauge wiring can cause voltage drop under load
• Utility voltage issue — brownouts or low voltage from the utility company during peak demand

Troubleshooting steps you can try

1. Check the outlet — plug a voltage tester or multimeter into the dishwasher’s outlet. You should read 110–125V. Below 105V under load indicates a wiring issue.
2. Reduce circuit load — if other appliances share the circuit (microwave, disposal, countertop appliances), unplug them and test the dishwasher alone.
3. Check for time-of-day pattern — if E27 only appears during evening hours, it may be a utility voltage issue. Contact your power company.
4. Inspect the plug and cord — ensure the power cord is firmly seated in the outlet and there’s no visible damage.

When to call a technician

If the outlet voltage tests normal and the circuit isn’t overloaded, the dishwasher’s internal power supply or control board may have a fault. A technician will test voltage at the board under load to isolate the problem. If it’s an electrical supply issue, an electrician (not an appliance technician) should inspect the circuit. Bosch recommends a dedicated 15A or 20A circuit for the dishwasher. Codes may vary by model generation and series.

Need help? Schedule Bosch Dishwasher repair with a certified technician, or contact our team for a free diagnosis consultation.