Quick diagnosis
What this code is telling you
Most likely trigger
Power surge or brownout during operation
Recommended replacement
Main Electronic Control Board
Diagnostic path
3 ordered checks
Part fit
Exact model number required
Safety first
Before opening the appliance
Unplug the appliance before removing panels or testing internal components. Do not bypass safety switches or live-test high-voltage, gas, refrigerant, or combustion components unless you are qualified to do so.
Read the full safety disclaimerRoot cause
Why the control reported this error
The cooking control displays this code when it detects an abnormal temperature, control, lock, or power condition. Verify power surge or brownout during operation first, then inspect for corrupted control board firmware and faulty power supply module before replacing main Electronic Control Board.
Symptoms
What you may notice
- ✓Oven shuts down immediately after start
- ✓Display displays E300
- ✓Settings menu resets repeatedly
Possible causes
Check the most likely causes first
- 1
Power surge or brownout during operation
Start here when it matches your symptoms.
- 2
Corrupted control board firmware
- 3
Faulty power supply module
Diagnostic sequence
Work through these checks in order
Stop when you find the fault. Do not perform a step that requires skills or live testing you are not qualified to do.
- 1
Check 1
Perform hard power reset by switching breaker off for 15 minutes.
- 2
Check 2
Disconnect electrical power before opening panels. Check incoming AC line voltage at terminal block.
- 3
Check 3
Replace main electronic power control module.
Replacement part reference
Main Electronic Control Board
Exact OEM part number
Model number required
Fitment note
The exact OEM part number varies by model and production revision. Verify the complete model number before ordering.
Verify the appliance model before ordering.
Manufacturers can use different parts under the same error code across model families and production revisions.
Where do I find my model number? →FixCodeDB may earn a commission from qualifying purchases made through affiliate links.
Common questions
Quick answers for this fault
What should I check first for E300?
Start with power surge or brownout during operation. If that checks out, continue through the diagnostic sequence above rather than replacing a part based on the code alone.
Does E300 always mean Main Electronic Control Board is bad?
No. An error code identifies the condition the control detected, not a guaranteed failed part. Confirm the likely causes and wiring first. The exact OEM part number varies by model and production revision. Verify the complete model number before ordering.
When should I stop troubleshooting E300 myself?
Stop if the next step requires live electrical testing, sealed-system work, gas or combustion service, or any procedure outside your training. Unplug the appliance before removing panels or testing internal components. Do not bypass safety switches or live-test high-voltage, gas, refrigerant, or combustion components unless you are qualified to do so.
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Keep diagnosing
Related Bosch guides
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E24 signals that the dishwasher is unable to drain water proper during the initial cycle drain check.
E305 signals an issue with the high-voltage inverter circuit or magnetron power supply line.
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