F45 Moderate Moderate DIY

LG Oven F45 — Box / cooling fan error

LG Oven · Error code F45

What F45 Means

The control cannot detect the box (cooling) fan running when commanded, distinct from the convection fan. Used on later LG ranges to differentiate cavity airflow from electronics cooling.

Symptoms

  • F45 or F-45 on display
  • Oven shuts down with controls warm to the touch
  • No air at top vent slot
  • Code may show up only on long bakes

Common Causes

1
Cooling fan motor failed

Bearings worn or windings open.

2
Fan blocked by insulation or debris

Loose insulation, twist-ties, or packing material in the cavity above the controls.

3
Tach feedback wire broken

Board sees no RPM signal even though fan spins.

4
Main board fan-drive failure

Output transistor or relay failed.

How to Fix It

  1. Power off at the breaker, let the oven cool, and remove the rear panel.
  2. Verify the cooling fan spins freely and there is no debris in the airflow path.
  3. Reseat the fan plug at both ends.
  4. Energize and confirm the fan spins when the oven is on; if it spins but F45 still trips, the tach lead or board is at fault.
  5. Replace the cooling fan motor if it does not run with voltage applied.
  6. Replace the main control board if voltage is missing at the fan plug.

Parts You May Need

If diagnosis points to a failed part, these are the common replacements. As an Amazon Associate we earn from qualifying purchases.

Common replacement LG oven cooling fan motor View on Amazon→

More LG Oven Codes

5b 5b — Sabbath Mode active (not a fault) CF1 CF1 — Left-front cooktop sensor open/short CF2 CF2 — Left-rear cooktop sensor open/short CF3 CF3 — Right-front cooktop sensor open/short CF4 CF4 — Right-rear cooktop sensor open/short F1 Range F1 — Upper Oven Thermistor Error

All LG codes → All oven codes →

Verified against manufacturer documentation: lgparts.com

Always unplug an appliance before servicing it. This guide is for informational purposes and is not a substitute for a qualified technician.