Why a tumble dryer overheats, and what to do about it

What is different about a dryer

Every other appliance in this site's corpus fails towards water or a shock. A tumble dryer fails towards fire. It holds a heating element or a compressor, a fan and a quantity of extremely fine, dry lint in one cabinet, and the faults that matter are the ones that let heat build where the lint is. That is why the danger wording on dryer pages here names fire rather than voltage, and why the urgent instruction is to take the washing out and spread it before anything else: an owner who has unplugged the machine has dealt with the shock risk and not the other one.

It is also why the manufacturers, who publish almost nothing for owners on most dryer codes, publish detailed cleaning procedures for the airflow path. Restricted airflow is how a healthy dryer becomes a hot one, and clearing it is the one repair they trust you with.

The airflow path, in order

The lint filter. In the door opening. Peel the mat of lint off in one piece rather than shaking or brushing it, then hold the filter up to the light. If you cannot see clearly through the mesh, or it feels waxy — fabric softener does this — rinse it under a warm tap with a little washing-up liquid and let it dry completely before refitting. Bosch and Samsung both make the drying point: a damp filter collects fibre far faster and the code returns within days. Bosch filters come in two halves that pull apart; clean both. Beko machines may take a double filter, and their eco filter has a cloth that must be attached to the frame — a bare frame looks right and filters nothing. Never run a dryer without the filter in place: AEG say so directly, because the lint then goes somewhere you cannot reach.

The condenser or heat exchanger. Behind the flap at the bottom front on a condenser or heat pump machine. Switch off and unplug first, put a cloth down because residual water may come out, release the catches or levers and lift the block out. Hold it up to the light: if you cannot see through the fins, that is your answer. Rinse it under a tap in the direction the air flows, or use a soft brush, and let it drain before it goes back.

Every manufacturer attaches the same two warnings here and they are worth taking literally. The fins are thin metal and sharp: AEG say "Do not touch the metal surface with bare hands. Risk of injury." And do not push a hard vacuum nozzle or anything rigid against them. AEG's wording is that it "may damages the ribs of the condenser, with leads to lower performance of the appliance and longer time drying" — the grammar is theirs, and the loss is permanent. Bosch say to flush with water only and use no hard or sharp-edged objects. Refit the block fully home with its catches locked, and check the inner cover latches: Samsung have a separate code, NC2, for a cover that looks closed but is not.

If your Bosch has no user-accessible heat exchanger behind the flap, it is a SelfCleaning model, and the equivalent of this job is the appliance care programme the machine prompts with CrE or CArE.

The plinth filter. Miele machines have a second filter behind the plinth at the bottom, in front of the heat exchanger. Clean it properly rather than brushing the surface, and look at its shape: Miele list a distorted, split or hardened plinth filter as a cause in its own right, and it is a consumable to replace rather than a repair. Beko call the equivalent area the toe board or kick zone and want it clean.

The room. A dryer in a cupboard, a small sealed utility room or a hot room cannot shed heat. Miele note that poor ventilation can raise the room temperature sharply and cause an airflow code with nothing broken; Samsung and AEG make the same point. Check nothing covers the ventilation opening in the base — a rug is enough — and on a vented machine follow the hose for kinks, crushing and a build-up at the outlet.

The load. Bosch give the test: level the load off and check you can fit a hand's width above it. An overloaded drum starves the airflow as effectively as a blocked filter.

How often? Filter every cycle — Miele and AEG both say so. Condenser or heat exchanger: AEG's own documents give intervals from monthly to six-monthly, and the code page here settles on monthly, because it costs nothing and takes fifteen minutes.

The codes that are airflow

Most of the caution-rated codes in this category resolve on the path above, and the code pages carry the manufacturer's own steps. Bosch E01 is a blockage in the filter or heat exchanger and comes with an eleven-step procedure; E06 is the filter. Samsung NC is the filter prompt and HC, a compressor overheating, is answered in their manual by cleaning the heat exchanger — not, as their website says, by an electrician checking a heating element the machine does not have. Hotpoint F10 and F15 are the two codes their manual says to clear by cleaning the filter and condenser, and the two their website handles worst. AEG E60, not heating, has airflow as its common cause; the condenser light is the most important reminder on the machine. Miele F66 has eight published causes and seven are yours. Beko F L t is the filters, all of them. The dryer taking hours to dry symptom page gathers the same family.

The codes that mean stop

A smaller set of codes name heat itself, and the manufacturers publish them without a retry. Read the absence of a remedy as the instruction.

• AEG [E70](/tumble-dryers/aeg/e70) — the temperature sensors. AEG say not to use the product until the problem has been completely fixed, unplug it and do not plug it back in until you are certain it is OK. A dryer that cannot read its own temperature has lost the only thing supervising the heat.
• Candy [F4](/tumble-dryers/candy/f4) — "Abnormal heating", and the entire published remedy is "Contact the customer service". The cause is either the heating side failing on or the air that should carry heat away not moving, and from outside you cannot tell which.
• Miele [F158](/tumble-dryers/miele/f158) — "The appliance has overheated". Miele publish filter-cleaning remedies on F55 and F66 and a load instruction on F50, and offer nothing here, not even a filter check. For a brand that forthcoming, the silence is deliberate: the safety thermostats intervened because the normal controls did not.
• LG [F1](/tumble-dryers/lg/f1) — "The temperature inside the drum has risen suddenly. Unplug the power plug and call for service."
• Samsung [HCL](/tumble-dryers/samsung/hcl) — a refrigerant leak from the sealed circuit of a heat pump machine. The refrigerant on these machines is R290, which is propane, in a small charge — Samsung's manuals give 0.149 kg — chosen because it is efficient and far better for the atmosphere than the alternatives, and flammable, which is why the circuit is sealed. Samsung's instruction is that the dryer is not to be used until the engineer has been, and the only permitted action is switching it off. Do that, leave the room ventilated, and call. R290 is a hydrocarbon rather than a fluorinated gas, so the F-Gas rules that apply to heat pump and air conditioning refrigerants are not the reason this is engineer work; the reason is that it is a sealed pressurised circuit of flammable gas.

On any of those: door open, load out and spread, unplug, and do not run the machine again to see. Cleaning the filter is worth doing on any dryer at any time. Running a machine whose code says "abnormal heating" to find out what happens is not.

The habit that matters more than any code

A dryer is the appliance people leave running while they are out or asleep, and the failure mode above develops over a cycle rather than instantly. The regulator's review of the Whirlpool-group campaign found that the modification reduced rather than eliminated the risk of lint fires on those machines, and the advice the code page here draws from that applies to any dryer with more force to a modified one: keep the filter and the machine itself scrupulously clean, and do not run it overnight or while the house is empty.

Who to call, and what it costs

There is no statutory register for appliance repair, so the person to call is a qualified appliance engineer, described by competence rather than by a card. Give them the exact code — Hotpoint's manual asks for both parts of a two-part code because they cannot tell what is wrong without them — and tell them what you have already cleaned.

The code pages' brackets are independent market estimates, because none of these manufacturers publish repair prices, and they run like this. Nothing at all where it is airflow, which is the common case: every airflow code above starts its range at zero. The overheating codes carry brackets of roughly £90 to £300 on most brands and £120 to £350 on a Miele, with a thermostat or temperature sensor at the bottom — an inexpensive part, the visit being most of the bill — and a control board at the top. A heating element or a fan motor with labour, the upper end of AEG's not-heating code, is bracketed to about £240. Sealed-system work on a heat pump machine — a compressor, or the refrigerant leak behind Samsung's HCL — is the expensive end at £150 to £450, and on an older machine will often exceed what the machine is worth; get the diagnosis confirmed before authorising it, since a sensor reporting a phantom leak is a far cheaper outcome. AEG commit to stocking temperature sensors for at least ten years after a model is discontinued, which is worth knowing before writing a machine off.

Sources

The cleaning procedures and the fin warnings are the manufacturers' own, as recorded on the code pages linked above, which cite the AEG, Zanussi and Electrolux support articles and manual, Bosch's heat exchanger procedure and display legend, Samsung UK's manuals, Hotpoint's instruction booklets, Miele's per-code articles and Beko's manuals and F L t guidance. The stop codes quote the manufacturers' published text as each code page records it. The R290 charge is from Samsung's DV9400B and DV90F24 manuals. The regulator's finding on the modification is from the Office for Product Safety and Standards' Whirlpool tumble dryer review of April 2019, recorded on the Hotpoint safety notice page. Cost brackets are the code pages' own.