LG F17 fault codewhat it means and how to fix it
Published by LG as a problem with the temperature sensor. Their F2 entry covers an unusable reading, so this is the sensor itself being at fault.
Take care
Get a qualified appliance engineer to look at your LG F17
We do not pass enquiries to a repair firm, so there is no form here. When you book a qualified appliance engineer, tell them the make, the model and the exact code or message on the display, and ask whether they carry parts for this make — that is what turns one visit into a repair rather than a quote.
What F17 means
LG publish two temperature-related codes and describe them differently, and the difference is the only thing distinguishing this page from that one. F2 is documented as a thermistor problem "causing the temperature in the unit to be out of range" — the reading has become unusable. F17 is documented as "a problem with the temperature sensor", with no reference to a range at all. Taken at face value, F17 is the appliance objecting to the sensing element rather than to the figure coming out of it, and that maps onto a real and different family of behaviour: a sensor that responds, but wrongly.
A thermistor that has drifted with age, one whose thermal contact with the surface it is supposed to be measuring has been lost, or one whose value moves erratically as the appliance vibrates all report numbers that are entirely plausible. Nothing looks impossible, so nothing trips the range check that produces F2.
What trips instead is a consistency check: the appliance knows roughly how fast the reading should move when the fan runs, when the magnetron cycles, when the door opens on a hot cavity. A sensor that fails to move when it should, or moves in a way the firmware cannot reconcile with what it is doing, gets rejected. That is why F17 tends to appear part-way through cooking on an appliance that started up perfectly well, while F2 is more often there from the moment you switch on. Both end in the same place. LG say F17 "will require service to resolve", and there is nothing an owner can reach without removing the outer cover, which on a microwave is the one thing never to do.
What causes it
| Cause | What is actually happening | How likely |
|---|---|---|
| Sensor drifted out of calibration | Years of heat cycling shift a thermistor’s curve, so it still reports believable numbers that no longer match reality. | Common |
| Sensor lost thermal contact | A clip that has relaxed or a probe pushed off its seat measures the air near a surface rather than the surface itself. | Occasional |
| Intermittent connection | A joint that makes and breaks with vibration produces a reading that jumps around, which fails a plausibility check rather than a range check. | Occasional |
| Wrong sensor fitted in an earlier repair | Thermistors of the same shape have different curves, and one substituted for another reads consistently and wrongly. | Rare |
Can you fix it yourself?
Stop — this needs an engineer
What it costs to fix
Typical repair cost
£70–£150
Time on site
1 hour
Sensor plus labour, so realistically £70 to £150 with a visit. If the engineer finds a connection rather than a failed part, the parts cost disappears and the visit does not.
Typical UK prices including parts and labour, updated September 2026. Your quote may differ.
Own this appliance and had this code? . Nothing is published until a person has read it.
Related LG fault codes
- F2Get it checkedLG describe a thermistor problem putting the temperature in the unit out of range. It is the reading that is wrong, not necessarily the cavity.Related: overheating and cooling
- F5Get it checkedLG call this a Damper Switch Error. A damper is the vent flap on an over-the-range model, so only those appliances can show it.Related: overheating and cooling
- F3Get it checkedLG document this one twice and differently. One article says wipe the touch panel, the other says the control panel is faulty and needs service.Related: same brand
- LOCUsually simple to fixNot a fault. LOC is LG’s child lock, and it releases by holding STOP/CLEAR until the display drops it.Related: same brand
- DOORGet it checkedThe word DOOR rather than a number. LG say the door is not closed or the latch is not engaged, and they include transit packing as a cause.Related: same brand
- F16Get it checkedLG say a heating issue was detected. They publish F19 with word-for-word identical text, so both codes land here.Related: same brand
Own a LG microwave? Save it and its codes come first next time.
Related guides
Common questions about LG F17
Should I be looking for F2 as well?
They are separate entries with separate published wording, and it is worth checking which one your display actually shows before quoting it to anyone. An engineer will investigate both around the same sensor and its wiring, but they are not the same code.
It appeared half-way through cooking.
That fits this code better than the other. A sensor producing plausible but wrong numbers passes every check until the appliance compares the reading against how fast it expects it to change, which only happens once something is heating.
Can I keep using it between failures?
Not sensibly. The appliance has told you it cannot rely on its own temperature sensing, and it is that sensing which decides when to cut the magnetron. Running it anyway means running without a protection it was designed around.
Technical review
Not reviewed by an engineer
No engineer has read this page. Severity follows what the manufacturer publishes, and we would rather tell you that than let a byline imply a sign-off.
Sources and how we verified this
We establish the facts from the sources below and then write the explanation ourselves. We do not copy manufacturer wording and we do not host their manuals.
- Manufacturer support portal
This page has not been reviewed by an engineer, and we would rather tell you that than imply otherwise. The severity rating follows what the manufacturer publishes: where they say isolate the appliance and call someone, so do we.