Bosch dishwasher — Error Code E27
Low voltage detected at the main control board power supply.
What it means
The E27 error code on a Bosch dishwasher is an under-voltage fault. The main control module monitors incoming line voltage to ensure safe operation of the wash motor and heating element. If the incoming AC voltage drops below the minimum operating threshold (typically under 105V on a standard 120V US circuit), the control board halts the cycle and triggers E27 to protect the internal electronics and motors from brownout damage. This code is rarely a failure of the dishwasher itself; it is almost always a symptom of an external electrical supply issue, such as a localized brownout, an overloaded household circuit, or degraded wiring at the junction box.
Likely Causes
- 1 Household Voltage Drop (Brownout)Temporary dips in the local power grid or heavy electrical loads in your home can drop voltage below the required 120V threshold.
- 2 Overloaded Electrical CircuitRunning multiple high-draw appliances (like microwaves or space heaters) on the same breaker circuit as the dishwasher starves it of voltage.
- 3 Burnt or Loose Junction Box WiringA loose wire nut connection in the dishwasher's junction box creates high resistance, leading to a significant voltage drop at the control board.
- 4 Faulty Power Cord or OutletA degraded power cord or a worn-out wall receptacle can restrict current flow, triggering the under-voltage sensor.
- 5 Failing Main Control BoardIf incoming voltage tests steady at 120V under load but E27 persists, the voltage-sensing circuit on the main control board has likely failed.
How to clear / reset
To clear the E27 code temporarily, perform a hard reset. Turn off the dishwasher and disconnect it from power by unplugging it or flipping the dedicated circuit breaker. Leave the power off for 5 to 10 minutes to allow the control board capacitors to discharge completely. Restore power and turn the unit back on. If the code was caused by a temporary grid brownout, the error will clear and normal operation can resume. However, if there is a persistent wiring issue or an overloaded circuit, the E27 code will return as soon as the wash pump or heater engages and drops the voltage again.
Common replacement parts
When to call a pro
You should call a professional if you have verified that your home's electrical circuit is supplying a steady 120V but the dishwasher continues to display E27. Diagnosing a faulty main control board or repairing burnt wiring inside the junction box requires specialized multimeter testing and carries a risk of electrical shock. Our technicians at Axis Appliance Repair can safely test the load voltage and replace damaged components. We offer a $90 diagnostic fee (waived if you proceed with the repair) and back our work with a 1-year parts and labor warranty.
FAQs
How much does it cost to fix an E27 code?
If it's a household electrical issue, you may just need an electrician. If the dishwasher's junction box or power cord is burnt, repair runs $120-$180. A failed control board can cost $250-$400+ including labor.
Can I fix the E27 error myself?
You can check your breaker box and test the outlet with a multimeter. If the outlet reads 120V, further disassembly to check the junction box or control board should be left to a pro due to electrical hazards.
Will the E27 code clear itself?
Yes, if the error was triggered by a temporary grid brownout, the dishwasher will often clear the code once steady 120V power is restored and the unit is restarted.
Will running the dishwasher with low voltage damage it?
Yes. Running motors and control boards on low voltage (brownout conditions) increases amperage draw, which generates excess heat and can permanently fry the wash pump or main board.
How long does it take to repair?
Replacing a burnt junction box or a faulty main control board typically takes a technician 30 to 60 minutes once the proper parts are on hand.
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