Bosch Dishwasher Error Code E03 — Auxiliary Heater Relay Fault
What this means
The E03 error points to a fault with the auxiliary heater relay on the main control board. This relay controls the secondary heating circuit used in drying cycles and high-temperature wash options. When it fails, the dishwasher may still wash but cannot properly heat during the drying phase.
Alternate codes: E3
Step-by-step fix
3 stepsPower cycle the dishwasher
Turn off the circuit breaker for 5 minutes, then restore power and run a cycle with the heated dry option.
A temporary relay glitch may clear after a full reset.
Inspect wiring connections
Unplug the dishwasher and check wire connections to the auxiliary heater for loose or burned terminals.
Burned or discolored wires near the heater connection indicate a wiring problem rather than a board issue.
Replace the control board
If wiring is intact, the auxiliary relay on the board has failed and the board needs replacement.
This is the same board as E01/E02 — if you have had multiple E-code errors, a single board replacement may fix them all.
When to call a professional
This repair involves internal electronics and the heating system. A qualified technician is recommended.
Related error codes
Information compiled from manufacturer service manuals, official troubleshooting documentation, and appliance repair industry resources. This guide is for informational purposes only — always consult a qualified technician for complex repairs.
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