LG F1 fault codewhat it means and how to fix it
The drum temperature has risen suddenly, and LG say unplug it and call. One LG manual also assigns this same code to a compressor failure, which is a documentation error worth knowing about.
Stop — this needs an engineer
Get a qualified appliance engineer to look at your LG F1
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 F1 means
LG label this a temperature error and give the cause as "The temperature inside the drum has risen suddenly", with the instruction "Unplug the power plug and call for service." No retry, no filter check, no intermediate step — just stop and call. On a dryer that is the right instruction, because a sudden rise in drum temperature is the beginning of the failure mode that sets dryers on fire, and LG are not asking you to investigate it.
Two complications, both about LG’s paperwork rather than your machine. The first is that we cannot be completely certain of the character. LG’s own manual PDFs and their HTML manual index render this code in a way that extracts as a capital I rather than a numeral one, in documents where the numeral one renders correctly two lines away in codes like 1F and tE1. Either their typeface uses a slab-serif one in that position, or the code genuinely is FI.
On a seven-segment display the two are near-indistinguishable, which is presumably why LG have never needed to settle it. The second is more serious: the RHX1009NNK manual prints this code twice, once as this temperature error and once as a compressor error with the cause "The compressor has malfunctioned". LG’s other manuals for the same code family assign the compressor fault to a different code entirely. That looks like an editing error, and it maps a compressor failure onto the same display as a drum overheat.
What causes it
| Cause | What is actually happening | How likely |
|---|---|---|
| Restricted airflow letting heat build in the drum | The standard mechanism behind any sudden temperature rise in a dryer. Air that should be carrying heat away is not moving, so the temperature climbs faster than the controls expect. | Common |
| A thermostat or heating control that has failed | If the control that should limit the temperature has failed, heating continues past the intended point. The sudden rise LG describe is the machine’s safety monitoring catching what the normal control missed. | Occasional |
| A temperature sensor reporting incorrectly | A sensor giving a wildly wrong reading produces this code with nothing actually overheating. It cannot be distinguished from the real thing without test equipment, which is part of why LG send you straight to service. | Occasional |
| A compressor fault, on one reading of LG’s documentation | The RHX1009NNK manual assigns this code to a compressor malfunction as well. LG’s other documents for the same family put that fault elsewhere, so treat this as a possibility raised by their own paperwork rather than an established meaning. | Rare |
Can you fix it yourself?
Stop — this needs an engineer
What it costs to fix
Typical repair cost
£100–£320
A thermostat or sensor is at the cheaper end, and compressor work on a heat pump machine is at the expensive one — which is one practical reason the documentation ambiguity matters. LG publish no repair prices, so these are independent market estimates.
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
- OEGet it checkedThe drain pump. But LG publish a second cause that no third-party site carries, and it explains why a dryer in a cold garage throws this code in January.Related: same brand
- 1FGet it checkedThe lint filter is not in the machine. Note this is not a dirty filter — LG have no code for that — and note it is one transposition away from a completely different fault.Related: same brand
- LE1Get it checkedThe motor stopped suddenly. LG give one owner check before their usual instruction, and it is worth doing because it is free.Related: same brand
- CCUsually simple to fixThe inner condenser cover is not fitted. This is a code that only appears after you have cleaned something, which makes it good news dressed as a fault.Related: same brand
Own a LG tumble dryer? Save it and its codes come first next time.
Related guides
Common questions about LG F1
Is my code F1 or FI?
Almost certainly the same thing, and you cannot tell from the display — a seven-segment display renders a one and a capital I nearly identically. LG’s own files are ambiguous too. We have published it as F1 because that is how it is universally known, while noting that LG’s documents extract as FI. Either way, you are on the right page.
Can I clean the filters and try again?
Cleaning the filters is always worth doing. But note that LG do not offer it as a step here — their instruction is to unplug and call, with nothing before it. On a code about the drum temperature rising suddenly, we would follow that rather than restarting to see what happens.
Which is it, a temperature fault or a compressor fault?
LG’s own documents disagree. One manual lists this code for both; their other manuals and their online manual index list only the temperature fault here and put the compressor fault under a different code. We flag it because an engineer arriving expecting one and finding the other wastes a visit. Mention both when you book.
Why is this rated dangerous when LG do not rate anything?
LG apply the same instruction to almost every fault they publish, from a drain pump to a drum overheat, so their classification does not distinguish by consequence. We do. A sudden rise in drum temperature sits next to dry lint and a heat source, which is a different kind of problem from a pump that will not run.
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 technical and service documentation
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.