Error F9 — cooling fault

This step-by-step repair guide walks you through fixing error f9 — cooling fault on your LG LSIS3018SS (Induction Range). With the right tools and parts, most homeowners can complete this repair in 1–2 hours and avoid a costly service call.

Part of our Top 20 Oven Models & Common Repair Issues Guide. Browse all oven repair guides for related models and issues.

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Common Symptoms & Causes

If your LG LSIS3018SS induction range is showing a cooling fault, you may notice one or more of the following symptoms before or alongside the error.

The control panel displays the “F9” error code during or after cooking
The range shuts off unexpectedly and will not resume operation
The cooling fan beneath the cooktop runs loudly, erratically, or not at all
The unit feels excessively hot to the touch around the control board area

This error is most commonly caused by a failed or obstructed cooling fan, a faulty fan motor, or a defective control board that can no longer regulate internal temperatures properly.

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Safety First

Unplug the oven from the power outlet before starting any repair — never work on a live appliance.
Wear work gloves when handling metal brackets, sheet metal edges, or sharp components.
Take photos with your phone before disconnecting any wiring harnesses or connectors.
Work in a well-lit area with enough floor space to lay removed panels flat.

Tools & Parts Needed

Essential Tools

Phillips #2 screwdriver
¼” nut driver
Multimeter
Work gloves (heat-rated)
Flashlight

Replacement Parts

Step-by-Step Repair Instructions

Step 1

Unplug the range from the wall outlet before doing anything else — the F9 error means the control board has detected an overheating condition, and working on a live unit risks electric shock. Let the appliance cool for at least 30 minutes so internal components return to a safe temperature. While you wait, inspect the rear vent openings and clear any accumulated lint or debris, since blocked vents are the most common trigger for this fault.

Step 2

Remove the rear access panel by taking out the four quarter-inch hex screws, then locate the cooling fan assembly. Spin the fan blade by hand — it should rotate freely with no grinding or stiff resistance; if it feels seized or drags, the fan motor bearings have failed and the motor must be replaced. A seized fan cannot move air across the induction board, which causes temperatures to spike and trip the F9 fault.

Step 3

Set your multimeter to the Rx1 (resistance times 1) scale and probe the fan motor terminals to test for continuity. An open reading — meaning the meter shows no continuity at all — confirms the motor winding has burned out and the motor needs to be replaced. Pro tip: also check the fan wiring harness connector for heat-melted pins or corrosion before condemning the motor itself.

Step 4

Locate the thermal fuse mounted in the main induction control board area and test it on the Rx1 scale with the multimeter. No continuity means the fuse has blown — this is a one-shot protective device that sacrifices itself when temperatures exceed a safe limit, and it will not reset. Replace the thermal fuse with an exact-rated replacement, because installing a higher-rated fuse removes a critical safety safeguard.

Step 5

With the unit still unplugged, measure the gap between the rear of the range and the wall — LG requires a minimum of two inches of clear space for adequate airflow. Restricted rear clearance starves the cooling fan of intake air, causing board temperatures to climb even when the fan itself is working perfectly. Reposition the unit if needed, and avoid pushing it flush against the wall after reinstalling the access panel.

Step 6

Plug the range back in, select a full-size induction zone, and run it at the highest power setting for 30 minutes to reproduce the conditions that originally triggered F9. If the error does not return, the repair is confirmed; if F9 reappears, the induction control board itself may have sustained heat damage and should be evaluated for replacement. Monitor the area around the unit during this test — any burning smell indicates a deeper electrical issue and the range should be unplugged immediately.

Where to Buy Replacement Parts

Find genuine OEM and aftermarket replacement parts for your LG LSIS3018SS (Induction Range) on Amazon:

When to Call a Professional

If the issue persists after completing all steps above, the problem may involve the sealed refrigerant system, a failed main control board, or wiring that requires specialized diagnostic equipment. Contact a licensed appliance technician — attempting sealed-system repairs without EPA 608 certification is illegal and unsafe.

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How Much Does This Repair Cost?

DIY repairs for an F9 cooling fault typically cost $20–$80, covering a replacement cooling fan or thermal fuse for the LG LSIS3018SS. A professional service call generally runs $150–$300 once you factor in labor and diagnostic fees. Tackling this repair yourself can save you $100 or more with just basic tools and a little patience.

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Frequently Asked Questions

Can I keep using my LG LSIS3018SS while the F9 error is active?

No, you should stop using the range immediately. The F9 error indicates a cooling fault that can cause overheating and potential damage to internal components.

What usually triggers the F9 cooling fault on this induction range?

The most common cause is a blocked or failed cooling fan. Dust buildup around the vents can also restrict airflow and trigger this error.

Will clearing the F9 error myself void my LG warranty?

Basic troubleshooting like cleaning vents typically won’t void your warranty, but replacing internal parts yourself may. Check your warranty terms before attempting any component-level repairs.

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