The E27 error on your Bosch dishwasher means the mains voltage at the appliance is too low — typically below 170V. The fault is in the household electrical supply, not the dishwasher itself, so the fix is usually checking the outlet, cord, and circuit rather than the machine.

Error code E27
Meaning Low mains voltage — supply below safe operating threshold
Severity Medium — DIY checks, then electrician (not appliance technician)
Time to fix 5–30 minutes for checks; electrician callout if needed
Tools needed Multimeter (optional — or just an electrician)

What the E27 error means

Bosch dishwashers monitor incoming voltage and refuse to start if it’s too low — typically under 170V. The motor and heating element won’t run safely on weak supply, so the control board protects itself by aborting and showing E27. The cause is on your side of the wall: a loose connection, a worn outlet, an overloaded shared circuit, or a brownout from the grid. Bosch’s own guidance is to call an electrician rather than a Bosch technician, because the appliance is fine — it’s the supply that isn’t.

Common causes

  • Dishwasher plugged into a power strip or extension cord (always use a dedicated outlet)
  • Worn or damaged outlet causing high resistance
  • Damaged power cord
  • Loose connection at the junction box behind the dishwasher
  • Shared circuit with another high-draw appliance (microwave, refrigerator, etc.)
  • Brownout or voltage fluctuation from the grid
  • Overloaded household electrical panel

How to fix the E27 error

  1. Unplug the dishwasher for five minutes. Restoring power may clear a one-off voltage dip. If E27 returns straight away, the supply is consistently low.
  2. Plug the dishwasher directly into a wall outlet. Power strips, extension cords, and surge protectors drop voltage under load. Bypass them and plug directly into the wall.
  3. Confirm it’s on a dedicated circuit. Dishwashers should have their own circuit. If yours shares with another major appliance, voltage drops when both run. Move it to a dedicated breaker.
  4. Inspect the power cord. Pull the dishwasher out and check the cord for damage, scorching, or signs of overheating at the plug.
  5. Test the outlet voltage with a multimeter. A working US outlet should read around 120V. Anything 10% under spec is a problem.
  6. Call an electrician, not an appliance technician, if the supply is consistently low. The fault is in the wiring or panel — and only a qualified electrician should diagnose it.

FAQ

Should I call a Bosch technician for E27?
No — the appliance is working correctly, it’s the electrical supply that isn’t. A Bosch technician will tell you to call an electrician, so save the callout fee and ring an electrician first.

Can I use an extension cord with my Bosch dishwasher?
Bosch (and most manufacturers) advise against it. Extension cords drop voltage under high-current loads and trigger E27. Always plug directly into a dedicated wall outlet.

Why does E27 only appear during the wash cycle?
The dishwasher draws the most current during the heating phase. A supply that’s marginal at idle drops below the threshold under heating load, which is when E27 trips.