E5
Bosch Induction Cooktop
Severity: ModerateWhat it means
Bosch induction hob E5 means the mains supply voltage has gone above the safe upper limit — typically above 260 V on a 230 V circuit.
The hob protects its electronics by disabling all zones until the supply returns to range.
E5 is rarer than E4 (low voltage) and usually points at a utility-side problem rather than something inside your home.
Affected Models
- Bosch Series 4/6/8 induction hobs (230 V, EU spec)
- Bosch induction hobs in rural or end-of-line distribution areas
- Bosch hobs on shared transformers with light commercial load
Common Causes
- Utility transformer running high during low-demand periods (often overnight)
- Failed or broken neutral wire raising one phase above its rated voltage
- Solar/battery system pushing local voltage up during sunny midday hours
- Faulty voltage regulator on a generator-backed supply
- Wiring fault that has connected the hob to two phases of a 3-phase supply
How to Fix It
-
Power the hob off completely.
Switch off at the wall or the consumer unit.
Leaving electronics on a supply that has tripped an overvoltage protection is asking for damage to other appliances too.
This is the most important first step — fixes come after the hob is isolated. -
Check other appliances and lights.
Are LED bulbs glowing brighter than normal?
Did the fridge make an unusual hum?
Did a UPS or surge protector chirp/click?
If yes, the overvoltage is house-wide, which points strongly at a broken-neutral fault — call an electrician immediately and tell them to test the supply at the meter. -
Measure the supply (if qualified).
An electrician can clip a meter on the incomer at the consumer unit and watch voltage over a few hours.
Anything that touches 253 V on a 230 V supply is out of statutory tolerance (UK) and the utility must investigate.
Don't attempt this yourself unless you're trained for it. -
Reset only after voltage is confirmed normal.
Once the supply is back in range — verified by a meter, not just hope — switch the hob back on and run a single zone on low power.
If E5 stays clear for 30+ minutes, the hob is fine and the issue was external.
If E5 returns within hours and the voltage is normal, the hob's overvoltage detection circuit may have failed — that's a Bosch service call.
When to Call a Professional
E5 is not something a homeowner should chase with tools.
Overvoltage on a domestic circuit is dangerous — it stresses every electronic device in the house, not just the hob.
If you confirm voltage is genuinely above 250 V at multiple sockets, contact your utility provider and an electrician on the same day.