E03 on a Bosch dishwasher
Bosch's list gives E03 as a main control board relay fault or error. In other words, one of the switches the board uses to power the pumps, heater or valves did not do what the board expected. The practical question is whether it was a one-off, after a power cut for example, or a lasting fault. A restart answers that: if E03 stays away, carry on; if it returns, the board and the parts it switches need testing.
Error codes
Reference| Code | Meaning |
|---|---|
| E03 | There is a main control board relay fault/error. |
Patterns seen with E03
- E03 appears after a power cut or storm — The board may have been upset by the supply.
- The dishwasher stops with water still inside — The cycle ended before draining.
- A part runs at the wrong time or not at all — The relay that switches it is not behaving.
- The code returns on several programmes — A sign of a lasting fault rather than a glitch.
Causes, most likely first
- A relay on the main board that has failed — First: relay contacts wear or weld after many switching cycles.
- A supply disturbance — Second: a power cut or surge during a programme can produce a one-off relay error.
- A shorted part stressing the relay — Third: a pump or heater drawing too much current can damage its relay.
- Moisture reaching the board — Fourth: water from a leak or overflowing suds can reach the electronics.
Checks, in order
- Think about recent power events — A storm or outage just before the code suggests a one-off.
- Restart the dishwasher — Breaker off for a few minutes, then run a short programme.
- Check for suds or leaks — Too much detergent, or the wrong kind, can cause foam that escapes.
- Note when the code appears — The stage of the programme helps identify the relay involved.
- Look at the filter and sump — A blocked filter makes the pumps labour, and a labouring motor is hard on the relay that feeds it.
What owners can do
- Restart from the breaker — Switch off, wait a few minutes, then switch on.
About 5 min
- Drain standing water — Run a drain or cancel programme if the dishwasher allows; otherwise bail out with a cup.
Tools: cup, towelsAbout 15 min
- Check the detergent — Use only dishwasher detergent, in the amount the manual gives.
About 2 min
- Run a short programme — Watch whether the code returns.
About 30 min
- Stop at the electronics — The board and the parts it switches are tested behind panels with the power isolated.
Tools: ::
Staying safe
Safety
Switch the dishwasher off at the breaker before bailing out water or cleaning the filter. Do not open the door panel or toe panel: the control board can hold a charge after the power is cut. If the breaker trips repeatedly or there is a burning smell, leave the dishwasher off until it is inspected.
When to get E03 checked
Get a professional in if E03 returns after a restart, if a part runs constantly, or if water is left in the tub repeatedly. They test the relay and the part it switches before replacing the board. A short note of when the code appeared and what the dishwasher was doing at the time makes the visit quicker.
Neighbouring dishwasher codes
Coverage of E03
This reading covers Bosch dishwashers that list E03 as a relay fault. It does not cover other Bosch appliances, or dishwashers of other brands where E03 has a different meaning. No model-specific E03 page exists yet; board layouts vary, so use the documentation for your model.
Bosch dishwasher codes
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