Quick diagnosis
What this code is telling you
Most likely trigger
Defective inverter control module
Recommended replacement
High Voltage Inverter Board
Diagnostic path
4 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 microwave control displays this fault after detecting an abnormal sensor, keypad, door, inverter, or heating condition. Check defective inverter control module first; failed magnetron tube and blown thermal cutout switch can trigger the same code and should be ruled out before replacing high Voltage Inverter Board.
Symptoms
What you may notice
- ✓Microwave starts for a few seconds then shuts down
- ✓E305 code flashes on screen
- ✓Food stays completely cold
Possible causes
Check the most likely causes first
- 1
Defective inverter control module
Start here when it matches your symptoms.
- 2
Failed magnetron tube
- 3
Blown thermal cutout switch
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
Disconnect power plug at wall outlet.
- 2
Check 2
Disconnect electrical power before opening panels. Check thermal fuse continuity with multimeter.
- 3
Check 3
Disconnect electrical power before opening panels. Inspect high voltage wiring leads between inverter board and magnetron.
- 4
Check 4
Disconnect electrical power before opening panels. Replace high voltage inverter control module.
Replacement part reference
High Voltage Inverter 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 E305?
Start with defective inverter control module. If that checks out, continue through the diagnostic sequence above rather than replacing a part based on the code alone.
Does E305 always mean High Voltage Inverter 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 E305 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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E011 indicates a key on the control console panel has been pressed or stuck closed for longer than 30 seconds.
E300 triggers when the main control board fails EEPROM checksum verification or loses system coding data.
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