How to reset a microwave, and what the display means

Why "unplug it" is only half the instruction

A microwave has a plug, which makes it the easy appliance on this site to isolate: pull the plug and it is off. Built-in models are the exception, usually fed from a switched fused spur in an adjacent cupboard or from the breaker, but the principle is the same. Every manufacturer in this corpus makes some form of power cycle the first move for a coded fault, and most of them attach a duration, which is the part people skip. The electronics hold their state for a few seconds after the supply goes; unplug and replug immediately and you have often reset nothing.

What the power cycle cannot do is make the inside of the appliance safe. A microwave holds a high-voltage capacitor that stays charged after the plug is out — Samsung, Whirlpool and Panasonic all put the instruction to discharge it before touching anything in their service manuals, and Samsung and Panasonic both say the charge remains for around thirty seconds after disconnection — a reason to leave the cover on, not a countdown after which it is safe. That is why nothing in this guide, and nothing in any manufacturer's owner procedure, involves the outer casing. A reset happens at the plug, the breaker and the buttons. Microwave faults: what you can fix, and what you must not open draws the rest of that line.

The reset, make by make

• Bosch, Neff and Siemens publish two versions and they agree. The troubleshooting database says to touch the clock button, and if the message does not go out, pull the mains plug and plug it back in after approximately ten seconds. The printed manual for the built-in models says to clean the control panel with a dry cloth, disconnect at the fuse box, and switch back on after ten seconds. For a jammed button — the E0532 answer — their instruction is to press every button individually, not to cut the power. The database adds one more step worth knowing: open and close the door, which makes the door switches change state and clears a stuck-input fault.
• Samsung unplug rather than press for five of their six codes. The stuck-key code C-d0 pairs the unplug with cleaning the touch panel, because dust or moisture is usually what is holding a key down. C-F2, the touch communication fault, is the one with a button remedy: press Stop and try again. For C-21, the high-temperature code, the instruction is to unplug, wait until it has cooled, and restart — the wait is the active part.
• LG attach the same first move to every F code: unplug at the socket, plug back in, and see whether the code returns. Their wording is that symptoms "may occur due to a temporary error". For E10, which LG describe as an internal short detected in the control board, they give a duration — unplug for one minute — and it is the only hardware fault in their table with an owner action attached. There is no button combination to clear an LG fault and no service menu an owner is given.
• Whirlpool are the most specific about timing. Their own failure-code table opens with the instruction: many of the problems in the chart may be solved by power cycling — unplug or disconnect power, wait one minute, then reconnect. Their public pages give the same procedure at the breaker for a built-in with no reachable socket, and add a second minute: watch the appliance for a further minute before cooking anything, because a code that returns within it has told you something real.
• Hotpoint combination microwave-ovens have two procedures and they are not the same thing. The ordinary power interruption — off at the isolating switch or breaker for a minute — clears a transient without losing anything. The published factory reset, reached through the settings control and Info, deletes all saved settings: clock, language, preferences and, on connected models, the network pairing. Keep that one for a code that survives a power cycle.
• Panasonic ask for thirty seconds unplugged for everything except the H codes, and the H codes are different in kind. On their inverter models the appliance counts events: three H97 or two H98 disable the oven permanently, and Panasonic state it stays disabled even after the faulty part has been replaced and the oven power-cycled. Clearing that needs a documented service sequence. An owner power cycle will not touch it, and nor should it — the counter exists to stop an oven being run repeatedly with a fault on its high-voltage side.
• Sharp combination models clear all four of their protection codes, E01 to E04, with one button: STOP/ECO. It is a cancel rather than a repair. For E01, overheating protection, let the appliance cool before pressing anything, because pressing STOP/ECO on a still-hot appliance invites the same protection a minute later.
• Miele give no reset, because their microwaves do not use codes and there is nothing to reset. Their checklist for a programme that will not start is: is the door closed, is the system lock on, is Food in oven? showing, is it plugged in and switched on at the socket, has the mains fuse tripped. Their instruction on the fuse is to stop rather than to reset it — these appliances are built to blow their own fuse deliberately if the door interlock monitoring detects a problem.
• Daewoo, De'Longhi, Statesman and other own-label combination models share one inherited fault table, E01 to E03, and the cancel button differs by badge even though the fault does not: STOP/CANCEL on Daewoo, PAUSE/CANCEL on Statesman and De'Longhi, STOP/ECO on Sharp.

The displays that are not faults

The cheapest fault on the site is a display that is doing its job, and microwaves have more of them than any other category.

• LOC on an LG, Child on a Panasonic, the key symbol on a Bosch, System lock on a Miele: child locks. LG's clears by holding STOP/CLEAR until the display drops it; Panasonic's by pressing Stop/Cancel three times; Miele's by holding OK for at least six seconds. Nothing needs unplugging.
• 12H or 24H flashing on an LG is the clock asking to be set. A flashing clock after a power cut is the same thing on most makes.
• DOOR on an LG and Close the door on a Miele mean the door has not latched: packing, a rack out of position, a turntable off its seat or debris on the frame are the common causes. A door that will not stay shut is the version to take seriously, because it goes on to blow the fuse.
• Demo mode — D or DEMO on a Panasonic, small squares on a Bosch, Demo mode on a Miele — is the showroom state where everything lights up and nothing heats. Its symptom is identical to a magnetron failure costing well over a hundred pounds, which is why it is the most expensive display to misread. Miele toggle it with OK held for at least four seconds; Panasonic and Bosch have their own sequences.
• Cooling and HOT or HOT INSIDE WAIT on a Panasonic describe normal operation and a warm cavity, and clear on their own. Fan running when off on a Hotpoint is documented normal behaviour. Keeping warm on a Miele is a feature, not the appliance restarting itself.
• Food in oven? on a Miele is a guard against running the appliance empty, shown when the door has not been opened for about twenty minutes. Heed it: running a microwave with nothing inside is the one thing an owner can do that reliably damages it, and the service manuals print the warning in capitals.
• Error on a Panasonic means two opposite things, separated only by timing. During programming it means a wrong or unavailable button. During cooking it means a fault, and Panasonic's instruction is to stop using the appliance and contact an authorised service centre.
• dEF1 is a defrost menu selection, not a fault.

When a reset is the wrong answer

A code that returns after one proper power cycle has passed the test the manufacturers set for it. LG's instruction is then an inspection, not another attempt; Whirlpool's second minute exists to catch exactly this; Bosch say to call with the code. Repeating the cycle does not gather more information, and on a microwave it can hide something. If the appliance went dead the moment the door was slammed, the monitor switch has very likely blown the internal fuse on purpose, because the interlock chain fell out of step — the right repair is a set of interlock switches, and a fresh fuse, or a fresh plug fuse, re-energises an appliance whose door switches are unproven. Samsung's C-21 carries the annotation "fire sensed", in their words; if there was smoke or flame, the recovery they publish is for the appliance, not permission to carry on as if nothing happened.

Codes nobody publishes

The published sets are short. Bosch name one microwave code in their printed manual, E-11, and dispose of the rest of the numeric space with a placeholder row reading Exx. Samsung publish six information codes and then say plainly that anything else needs a technician. Panasonic list eleven H codes and explain four, in hedged terms. LG publish twelve F codes with no F6 to F10, no F12 and no F18 anywhere in their documentation, whatever third-party tables claim. Sharp publish four; twenty-five of their twenty-seven current UK manuals have none at all. Miele publish none.

So if your display shows a code that is not on your manufacturer's page — Samsung's C-10, C-A0, C-70 or C-d2, which appear on repair sites and not on Samsung's own UK page, or an LG F-number in one of the gaps — this site cannot tell you what it means, and neither can anyone quoting a longer table, because the manufacturer has not said. What you can do is what the manufacturer says for everything they do not explain. Samsung's rule is unplug the appliance and contact Samsung. LG's is one power cycle and then an inspection. Bosch's is the generic BSH instruction for any message beginning E: switch off and on, and call with the code if it stays. Give the exact string, including hyphens and leading zeros, when you ring — BSH print the same code as E-3, E3 and E3 00 depending on the document, and Samsung publish the same condition as C-d0, -SE- and SE across model generations.

What it costs

Nothing, for most of this page: a lock, a clock prompt, a demo mode or a door that needs closing is a call-out people pay for every week and should not. Where a reset does not hold, the code pages carry the brackets: a touch panel or fascia £80 to £130 fitted; a sensor £70 to £160; a control board £90 to £220 depending on the make; a magnetron, inverter or transformer £100 to £300, the upper end being built-in models that have to come out of a housing. On a countertop machine most of those exceed what the appliance is worth, which is a fair reason to replace it — but replace it rather than running it with a fresh fuse and a door that has not been checked.

Sources

• Bosch built-in microwave instruction manuals and the BSH UK troubleshooting database (E-11, Exx, E0532, the key symbol, demo mode, "Temperature too high"; the clock-button and ten-second resets).
• Samsung UK, "Displayed information codes on my microwave" (the six codes, their remedies, and the statement that anything else needs a technician).
• LG microwave error code help-library article (F1–F19, E10 with the one-minute instruction, LOC, DOOR, 12H).
• Whirlpool tech sheet W11381054 Rev A (2020) and Whirlpool product help for built-in microwaves (the power-cycle instruction and its timing).
• Hotpoint combination microwave-oven manuals (the F table and the factory reset warning).
• Panasonic UK consumer troubleshooting for microwave display codes and Panasonic inverter microwave service manuals (H95/H97/H98/H99, the event counter, Error, Cooling, HOT, D, Child).
• Sharp SDA_MAN_0119 and SDA_MAN_0220 combination manuals (E01–E04 and STOP/ECO); Daewoo SDA2094 and SDA2093, Statesman SKMC0925 and De'Longhi D90N30 manuals for the shared table.
• Miele microwave operating instructions, problem-solving guide.
• Whirlpool service documentation on discharging the high-voltage capacitor, as quoted on this site's microwave pages; Samsung microwave service manuals (M1713, CE2733R, special high-voltage precautions) and Panasonic inverter service manuals (NN-S573MF, NN-CD557WEPG), both of which state that the capacitors remain charged for about thirty seconds after disconnection and must be discharged before touching any component.