Bosch Cooktop U400 error code
- Cooktop
On Bosch cooktops, error U400 indicates: Supply voltage is incorrect — call the utility or an electrician. Start with a 5-minute power reset at the breaker, then follow the cooktop-specific checks below before ordering replacement parts for U400. If the code returns on two consecutive cycles after a reset, treat it as a confirmed fault — not a one-time power glitch.
Reviewed August 2025 · sources below
Safe to keep using?
No safety issue
This is a status or lock code, not a hardware fault.
How to fix U400
- Unplug the cooktop or turn off power at the breaker before inspecting any components.
- Reset Bosch U400: leave power off for 5 minutes, restore power, then restart. Confirm whether U400 returns.
- Check the most common cause for U400: Supply voltage is incorrect — call the utility or an electrician.
- Wipe the glass dry, move pans off the controls, and confirm the cookware is induction-ready and centered if the zone is induction.
- If a reset and basic checks don't clear the code, use our lookup tool for AI-powered diagnosis or contact a qualified technician.
- Reassemble, restore power, and run a test cycle. If U400 returns, the faulty component likely needs replacement.
Call a pro when: Call a technician if you smell burning, see sparking, hear grinding from the motor, or the code returns after replacing the suspected part.
Next step
Still having trouble after the code fix?
This code is usually a status or maintenance notice, not proof of a failed part. Try the steps above first; then describe what still isn't working.
Free guided checks · No account required · Don’t open live electrical, gas, or refrigerant equipment
What U400 means
Supply voltage is incorrect — call the utility or an electrician.
Likely causes
Supply voltage is incorrect — call the utility or an electrician.
Check: Press Power or Start/Pause to clear the code, then restart the cycle.
Est. cost: $0–$0
Electric dryers and ranges need both hot legs; a miswired cord reads as low voltage.
Check: Confirm the cord matches the outlet type and each hot wire is on the correct terminal.
Est. cost: $0–$150
Guided repair checklist
Complete the safe checks one at a time. Progress is saved for this browser so you can continue later.
0 of 6 checks recorded
Recommended next action
Start with this check before considering replacement parts.
Check 1 of 6
Unplug the cooktop or turn off power at the breaker before inspecting any components.
Did the repair resolve the issue?
Restoring repair progress…
Questions about U400
What does U400 error code mean on a Bosch cooktop?
Supply voltage is incorrect — call the utility or an electrician.
How do I reset Bosch cooktop U400?
Unplug the cooktop or switch it off at the breaker for 5 minutes, then restore power and restart. A reset clears a stored U400 after a glitch, but the code will return if the underlying fault is still present.
What part do I need for Bosch U400?
Not always — some U400 errors are caused by user-fixable issues like clogs or unbalanced loads. Try the troubleshooting steps first.
Can I fix Bosch error U400 myself?
Many U400 errors can be fixed DIY if you're comfortable with basic tools. Start with the reset and steps above. If the issue involves electrical components or the code returns after replacing parts, call a professional.
Other Bosch Cooktop codes
Prevent this problem next time
- Use lock features only when needed
- Avoid cutting power mid-cycle
Sources
Manufacturer meaning
Supply voltage is incorrect — call the utility or an electrician.
FixApplianceCode guidance
Clear the U400 status code and restart. No replacement part is needed.
Source type: Editorial
Source: FixApplianceCode status-code guidance
Last reviewed: 2026-10-24
Repair guidance is for informational purposes only. We do not guarantee that any fix will resolve your issue, and you assume all risk when following these steps. Terms & disclaimer
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