E04
Bosch Washing Machine
Severity:What Does This Error Mean?
E04 on a Bosch washer means the heater element or its sensor has failed. Hot wash cycles will not complete. Power off for 10 minutes. If E04 returns, the heater needs replacement — book Bosch-authorised service.
Affected Models
- Bosch WAW28460GB
- Bosch WAT28401UC
- Bosch Serie 8 WAX32EH0BY
- Bosch WAU28PH9SN
- Bosch WLG24260BY
Common Causes
- Failed heating element (often after limescale build-up causes overheating)
- Failed temperature sensor (NTC thermistor)
- Loose harness connector at the heater terminals
- Tripped heater thermal cutout (in some models, manually resettable)
How to Fix It
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Power off for 10 minutes.
Switch off at the wall socket. A long power-off allows the heater thermal cutout (if tripped) and sensor reads to reset. Restore power and try a cold cycle.
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Try a cold-only cycle.
Select Cold Wash. The heater is not used at cold settings. If the cycle completes normally, the cooling and motor sides are fine — E04 is isolated to the heater.
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Run descale (if available).
Some Bosch washers have a descale or care cycle. Run with the recommended descaler. Limescale on the heater is a leading cause of E04 — descaling extends heater life.
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Book Bosch service.
A Bosch washer heater costs USD 70–130 for the part. Labour and access add USD 200–300. Bosch heaters sit behind the front panel on most models — the technician removes the front to access.
When to Call a Professional
E04 typically requires opening the front of the washer to access the heater. Book Bosch-authorised service — heater element replacement is not safe DIY for most users.
Frequently Asked Questions
Can I run cold washes with Bosch E04?
Yes — cold cycles do not use the heater and complete normally. As a workaround you can use cold-only washes while waiting for service. You lose hot wash, sanitise, and descale cycles — all of which need the heater.
Why did my Bosch washer heater fail?
Most Bosch washer heaters fail after years of limescale build-up. The scale insulates the element, causing it to overheat and burn out. In hard-water areas, monthly descaling extends heater life by years. Use the right detergent dose and water softener treatment if your area is very hard.