E03 — Water not heating
Per Bosch's official US error-code page, E03 is a main control board relay fault/error (Bosch uses the same wording for E02 and E03).
- Keep using it?
- Limited use only
- DIY difficulty
- Moderate
- Typical cost
- $35-75
- Verified against
- bosch-home.com ↗
The fix
Water inlet valve
Water fill / inlet issue
Diagnose first: Check household water supply first; if open, inlet valve solenoid is most common failure.
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How to fix it
- Verify the hot water supply valve under the sink is fully open.
- Run hot water at the sink for 30 seconds before starting the dishwasher.
- Check incoming water temperature with a thermometer (target 120 deg F).
- Inspect the heater for visible scale buildup; descale with citric acid cycle.
- If heater resistance is high or NTC is drifted, replace those components.
Why it happens
Typical signs: Cool wash water · Cycle runs long then errors · Dishes greasy after cycle
- Cold water supply only Hot supply valve closed, dishwasher cannot reach setpoint in time.
- Heater partially failed Element degraded but not fully open.
- Limescale on heater Insulation from mineral buildup slowing heat transfer.
- Control thermistor drifted NTC reading high, ending heat cycle early.
Other parts sometimes needed
If diagnosis points to a failed part, these are the common replacements. As an Amazon Associate we earn from qualifying purchases.
- Bosch dishwasher descaler Common replacementAmazon →
More Bosch dishwasher codes
Always unplug an appliance before servicing it. This guide is for informational purposes and is not a substitute for a qualified technician. Verified against manufacturer documentation: bosch-home.com.