EN

Severity: Low

Bosch Dishwasher Error E27 – Supply Voltage Too Low

The Bosch measured too little voltage from the house circuit and stopped. Usually wiring, outlet or load.

At a glance

Severity: 2/5 – Low2/5

Severity: Low

Meaning
Supply Voltage Too Low
Typical repair cost
$0–$800
DIY difficulty
Easy

Bosch lists E:27 as insufficient house power supply: the dishwasher's electronics measured a line voltage below what they need to run the heater and pumps safely. A US Bosch runs on 120 V and, during heating, draws most of what a 15 A circuit can deliver, so any weak link shows up as a voltage sag the moment the heater switches on. Typical weak links are a loose wire nut in the junction box behind the toe kick, a worn or back-stabbed outlet under the sink, a circuit shared with the garbage disposal or a countertop appliance, or a long run on thin wire. Bosch's own advice is a breaker reset and, if the code comes back, an electrician to check the incoming voltage.

How it looks on the display

Bosch Dishwasher display showing error E27

Model families & display variants

Model familyShowsNote
100, 300 and 500 SeriesE:27Shown on the top-of-door display.
800 Series and BenchmarkE:27Same code; these models draw similar power during the heat phase.
Older Bosch modelsE27Same meaning without the colon.

Safety first · Consult a professional

Don't open the junction box or outlet with the breaker on. Checking voltage under load and tightening connections is electrician work; a loose connection that causes E:27 can also overheat.

  • Unplug the appliance or switch off the breaker before opening any panel. Mains voltage can kill.

Symptoms

  • E:27 when the cycle reaches its heating phase
  • Kitchen lights dim briefly when the dishwasher starts heating
  • Code appears more often when the microwave, toaster or disposal runs at the same time
  • Dishwasher stops but restarts normally after a breaker reset
  • Outlet or cord plug under the sink feels warm or looks discolored

Possible causes

Ranked by how often each cause is behind this code (editorial estimate).

  1. Loose or corroded connection in the junction box, outlet or wire nuts 30%
  2. Dishwasher shares a circuit with the disposal or countertop appliances 25%
  3. Worn outlet, switched outlet or extension cord in the supply path 15%
  4. Voltage sensing on the dishwasher's power module faulty 12%
  5. Low utility voltage or neighborhood brownout 10%
  6. Undersized or very long branch circuit wiring 8%

Fix it step by step

Diagnostic flow: E271Reset the breaker2Remove the extras3Run it alone4Look for heat damage5Have the voltage measured under load

  1. Reset the breaker

    Hold Start for 3 seconds, switch the dishwasher's breaker off for 30 seconds and back on, then start a normal cycle. If E:27 doesn't return, note the time of day and what else was running.

  2. Remove the extras

    If the dishwasher is plugged in, make sure it goes directly into the wall outlet, not through an extension cord, power strip or adapter. Check whether the outlet is controlled by the disposal switch.

    Tools: Flashlight

  3. Run it alone

    Start a cycle with no microwave, toaster, kettle or disposal in use. If E:27 disappears, the circuit is overloaded or its wiring can't carry the combined load.

  4. Look for heat damage

    With the breaker off, look at the plug, outlet face and cord for discoloring or a melted edge. Any sign of heat means stop using the dishwasher until an electrician has fixed the connection.

    Tools: Flashlight

  5. Have the voltage measured under load

    An electrician measures at the dishwasher while it heats. Normal is roughly 114 to 126 V; a drop of more than a few volts when the heater kicks in points to a bad connection or overloaded circuit. If the voltage holds steady and E:27 still appears, the dishwasher's power module is suspect.

    Tools: Multimeter

How to reset E27

  1. Hold Start for about 3 seconds to cancel the cycle.
  2. Turn off the breaker for 30 seconds and switch it back on.
  3. Start a cycle with other kitchen appliances off; if E:27 returns, call an electrician.

Where the parts are

Dishwasher: filter, drain pump and sump – E27123456789
Dishwasher: filter, drain pump and sump
  1. 1Door lock
  2. 2Water inlet valve
  3. 3Filter
  4. 4Circulation pump
  5. 5Heating element
  6. 6Drain pump
  7. 7Float switch
  8. 8Temperature sensor
  9. 9Water level sensor

Repair options & costs

RepairDIY?Estimated cost
Plug directly into the outlet, rebalance kitchen loads Yes $0
Electrician: tighten connections, replace outlet No $120–$250
Dedicated dishwasher circuit No $300–$800
Replace dishwasher power/control module No $350–$600

Rough US estimates; technician call-out fees vary by region. Not a quote.

When to call a technician

Call a licensed electrician first if E:27 keeps returning, lights dim when the dishwasher heats, or any plug or outlet shows heat marks. Bring in Bosch service only after the electrician confirms steady voltage at the dishwasher under load.

Frequently asked questions

Is E27 a problem with my dishwasher?

Usually not. The code reports what the dishwasher sees coming from the house. Most fixes are in the outlet, junction box or circuit, which is why Bosch points you to an electrician.

Does a Bosch dishwasher need its own circuit?

Check the installation instructions for your model; Bosch calls for a properly sized circuit, and many local codes require a dedicated one. Sharing with a disposal or countertop appliances is a common trigger for E:27.

Can a GFCI outlet cause E27?

A GFCI that trips cuts power completely, which usually just turns the unit off. A worn GFCI with poor internal contacts can drop voltage under load, so it is worth having it checked along with the rest of the circuit.

Why only in the evening?

When many homes run appliances at the same time, supply voltage can sag slightly. On a circuit that is already marginal, that small drop can be enough to trigger the code.

Sources