Bosch [E27] fault codewhat it means and how to fix it

E27 is one of the most useful codes Bosch publish, because of a sentence most manufacturers would never write. Their manual gives the meaning as the mains voltage being too low and then adds, in their own words, that this is not a fault on the appliance. The instruction that follows is to contact an electrician and have the mains voltage and electrical installation checked.

Bosch UK add a specific figure worth knowing: the mains voltage is usually below 170 volts when this appears. UK mains sits nominally at 230 volts, so 170 is a long way down and points at something real rather than a marginal reading. This matters commercially as well as technically. A reader who sees a fault code on a dishwasher naturally books a dishwasher engineer, and for this code that is money spent to be told the appliance is fine. The problem is in the wiring, the socket, or occasionally the incoming supply.

If other things in the kitchen have been behaving oddly — lights dipping when something switches on, other appliances tripping — that is corroboration rather than coincidence, and it is worth mentioning to whoever you call.

1. 1

   Look at what the machine is plugged into. If it is an extension lead or a multi-way adaptor, move it to a wall socket of its own — that alone resolves a good share of these.

   If there is any scorching, discolouration or a smell of hot plastic at the plug or socket, stop, switch off at the consumer unit and call an electrician. Do not plug it back in.
2. 2

   Plug something else demanding into the same socket — a kettle is ideal — and see whether it behaves normally. A second appliance struggling points at the socket rather than the dishwasher.

3. 3

   Notice whether the problem coincides with other heavy appliances running. Voltage sag that only appears when the washing machine heats suggests an overloaded circuit.

4. 4

   Call an electrician rather than an appliance engineer. This is Bosch’s own instruction for this code, and an appliance repairer is not qualified to work on your house wiring anyway.