LG Microwave F11 Error Code: Inverter Communication Error (What to Do)

What the code means

LG's service manual for the LMC1575 NeoChef countertop models (P/No. MFL69902602, February 2017) lists F-11 in its error code table as "Inverter communication Error", alongside F-3 key error, F-4 humidity sensor error and the inverter fault codes F-13 to F-17 and F-19. Its inverter troubleshooting page shows the symptom as "Not heating (F-11)" and has the technician check the connection between the inverter PCB and the main PCB (connectors CN3 and CN8) for an open or short. The remedy steps are: check the communication harness at the PCB connectors, check the connector pins with a tester for open or short, replace the inverter PCB if the connector is shorted, and check the inverter's IC parts. LG's own help library has an "LG Microwave Oven - F 11 Error Code" article filed under inspection codes F-1 to F-19, and LG's general microwave error-code guidance says these codes indicate a failure mode: unplug the power cord, plug it in again after 2 to 3 minutes, and if the problem isn't solved, service is required. LG's USA help library adds that F codes other than F-3 can indicate defective parts, short circuits, communication failures or overcurrent, so an inspection by a technician is recommended. Appliance Aid's LG NeoChef table gives the same meaning (inverter communication error, a wiring or inverter issue). F11 only applies to inverter models. Appliance Aid lists a different F-11 on some older LG convection combination ovens, where it means the oven stayed above 100 C after the 30-minute maximum in convection mode, so check which kind of microwave you have.

Likely causes

• A loose, damaged or corroded harness or connector between the main control board and the inverter board (LG's manual checks this first)
• A failed inverter PCB (LG's manual says to replace it if the communication connector tests shorted)
• A fault on the main control board side of the link
• A temporary glitch, for example after a power outage or surge, that clears after a power reset

Safe DIY checks

1. Unplug the microwave (or switch off its breaker) for 2 to 3 minutes, then plug it back in. That is LG's first step for F codes.
2. Try a short heating test with a cup of water. If F11 doesn't return, it was a temporary error.
3. Make sure the microwave has its own properly rated outlet and isn't sharing the circuit with another high-draw appliance like a toaster or kettle.
4. Note whether F11 appeared after a power outage, a surge or a recent repair, and give that to the technician.
5. Don't open the cabinet. The inverter and its capacitors are high-voltage parts that can hold a dangerous charge after unplugging.

Parts that commonly fix it

Always match the part number to your exact model.

Related codes

• F3 LG Microwave F3
• F4 LG Microwave F4
• LOC LG Microwave LOC
• E-11 Frigidaire Microwave E-11
• F3 GE Microwave F3

All LG codes →

Sources

1. LG LMC1575BD/ST/SW/SB microwave service manual MFL69902602, p.34 error code table (F-11 Inverter communication Error; check harness and connector pins, replace inverter PCB if shorted) (ManualsLib copy)
2. Same LG service manual, p.36 inverter PCB troubleshooting (Not heating (F-11): check CN3/CN8 connection for open or short) (ManualsLib copy)
3. LG Egypt help library: LG Microwave Oven - F 11 Error Code (inspection codes F-1 to F-19)
4. LG Sri Lanka help library: Microwave error codes (failure mode; unplug 2 to 3 minutes; service required if not solved)
5. LG USA Support: LG Microwave - Troubleshooting an F3 Error (other F errors can mean defective parts, short circuits, communication failures or overcurrent; inspection recommended)
6. Appliance Aid: LG Microwave Fault Code Chart (NeoChef F-11 inverter communication error; older convection-model F-11 meaning)