Microlife thermometer screen: what H, L, AH, AL, ERP, Er 2 and Er 6 mean
Microlife’s instruction manuals for the IR 310 ear thermometer and the NC 200 non-contact thermometer name every state below. Each one has Microlife’s own words in quotation marks, what Microlife says to do, the model it comes from, and a link to our page on the same symbol across other makes.
Check your thermometer’s manual — makers differ.
All 13 Microlife screen states at a glance
| On the screen | What Microlife’s manual says it means |
|---|---|
H | Measured temperature too high (IR 310 and NC 200) |
L | Measured temperature too low (IR 310 and NC 200) |
AH | The room is too warm (IR 310 and NC 200) |
AL | The room is too cold (IR 310 and NC 200) |
ERP | The probe is not in the ear correctly (IR 310) |
Good | The probe is in the right position (IR 310) |
Probe cover icon and a red screen | No probe cover on the sensor (IR 310) |
Red screen and 10 short beeps | Fever alarm at 37.5 °C or above (IR 310 and NC 200) |
Er 2 | The thermometer touched the forehead or object (NC 200) |
Er 0 or Er 6 | A fault in the thermometer (NC 200) |
Flashing battery icon | The battery is getting low (IR 310) |
Battery icon alone | The battery is flat (IR 310) |
M with a number | Memory: past readings (IR 310) |
Which models this covers
Two Microlife manuals were read: the IR 310 ear thermometer and the NC 200 non-contact (forehead and object) thermometer. Each state says which model it comes from, because the limits differ: AL starts below 10.0 °C on the IR 310 but below 15.0 °C on the NC 200 in body mode. Microlife makes many other thermometers, including stick models such as the MT 410, whose manuals are separate.
Each state, in Microlife’s words
H Measured temperature too high
Microlife IR 310 and NC 200
“Displays «H» when measured temperature is higher than 43 °C / 109.4 °F.”
The NC 200 manual gives the same 43 °C limit in body mode and 99.9 °C / 211.8 °F in object mode. The NC 200 manual’s fix: “Make sure the measuring sensor is clean. Then, take a measurement again.”
Every make: Hi on a thermometer. Source: Microlife Ear Thermometer IR 310 — instruction manual (IB IR 310 N-V10, PDF) Checked 2026-10-13.
L Measured temperature too low
Microlife IR 310 and NC 200
“Displays «L» when measured temperature is lower than 32 °C / 89.6 °F.”
The 32 °C floor is the IR 310 ear thermometer’s. The NC 200 manual puts L lower than 34 °C / 93.2 °F in body mode and 0.1 °C / 32.2 °F in object mode. The NC 200 manual’s fix: “Make sure the measuring sensor is clean. Then, take a measurement again.”
Every make: Lo on a thermometer. Source: Microlife Ear Thermometer IR 310 — instruction manual (IB IR 310 N-V10, PDF) Checked 2026-10-13.
AH The room is too warm
Microlife IR 310 and NC 200
“Displays «AH» when ambient temperature is higher than 40.0 °C / 104.0 °F.”
The A stands for ambient: AH and AL are about the air around the thermometer, not about the person. The NC 200 manual’s fix for both: “Allow the thermometer to rest in a room for at least 30 minutes at ambient temperature.”
Every make: Room too hot or too cold. Source: Microlife Ear Thermometer IR 310 — instruction manual (IB IR 310 N-V10, PDF) Checked 2026-10-13.
AL The room is too cold
Microlife IR 310 and NC 200
“Display «AL» when ambient temperature is lower than 10.0 °C / 50.0 °F.”
That 10.0 °C limit is the IR 310’s. On the NC 200, Microlife puts AL below 15.0 °C / 59.0 °F in body mode and below 5.0 °C / 41.0 °F in object mode.
Every make: Room too hot or too cold. Source: Microlife Ear Thermometer IR 310 — instruction manual (IB IR 310 N-V10, PDF) Checked 2026-10-13.
ERP The probe is not in the ear correctly
Microlife IR 310
“Display «ERP» when the probe is not correctly inserted in the ear canal.”
What Microlife says to do: “Please insert the probe as described in this manual.”
Microlife’s steps: after the beep, gently pull the middle of the ear back and up, then place the probe firmly in the ear canal until “Good” appears.
Every make: POS, ERP or Er 2. Source: Microlife Ear Thermometer IR 310 — instruction manual (IB IR 310 N-V10, PDF) Checked 2026-10-13.
Good The probe is in the right position
Microlife IR 310
“The probe LED light will stop flashing (stays illuminated) and good will be displayed on the LCD, when the measuring sensor detects an appropriate position.”
What Microlife says to do: “Press the START/IO button and keep the probe in the ear until the thermometer beeps to signal the completion of the measurement.”
Good is the opposite of ERP: once it shows, the position is right and you can start the reading.
Every make: POS, ERP or Er 2. Source: Microlife Ear Thermometer IR 310 — instruction manual (IB IR 310 N-V10, PDF) Checked 2026-10-13.
Probe cover icon and a red screen No probe cover on the sensor
Microlife IR 310
“Displays probe cover icon with a red LCD backlight to remind the user to put on a new undamaged probe cover before each measurement.”
What Microlife says to do: “Fit a new Microlife branded and undamaged probe cover on the measuring sensor.”
The same icon also shows for 3 seconds when you switch off, as a reminder to take the used cover off. A red screen with this icon is about the cover; a red screen with a temperature is the fever alarm.
Every make: Lens filter or probe cover symbol. Source: Microlife Ear Thermometer IR 310 — instruction manual (IB IR 310 N-V10, PDF) Checked 2026-10-13.
Red screen and 10 short beeps Fever alarm at 37.5 °C or above
Microlife IR 310 and NC 200
“10 short beeps and a red LCD backlight alert the patient that he/she may have a temperature equal to or higher than 37.5 °C.”
Microlife gives the normal range for these thermometers as 35.4 – 37.4 °C / 95.7 – 99.3 °F, and reminds you that readings from different measuring sites should not be compared.
Every make: Fever colours and fever symbol. Source: Microlife Ear Thermometer IR 310 — instruction manual (IB IR 310 N-V10, PDF) Checked 2026-10-13.
Er 2 The thermometer touched the forehead or object
Microlife NC 200
“Er 2 : Device is directly placed on the forehead / object.”
What Microlife says to do: “Keep the measuring distance of 1 - 5 cm. Do not touch the bottom side (sensing area) of the measuring sensor.”
The NC 200 is a non-contact thermometer: it starts on its own when the sensor finds the right distance, and a green light on the back confirms it.
Every make: Err or Er with a number. Source: Microlife NC 200 non-contact thermometer — instruction manual (IB NC 200-e N-V10, 2026-08-17, PDF) Checked 2026-10-13.
Er 0 or Er 6 A fault in the thermometer
Microlife NC 200
“Er 0 / Er 6 : The system has a malfunction.”
What Microlife says to do: “Remove and reload the battery and reboot the device. If the message still appears, please contact the Microlife local retail or distributor.”
Of the three codes in the NC 200 table, only Er 2 is about how you measured; Er 0 and Er 6 are the thermometer itself.
Every make: Err or Er with a number. Source: Microlife NC 200 non-contact thermometer — instruction manual (IB NC 200-e N-V10, 2026-08-17, PDF) Checked 2026-10-13.
Flashing battery icon The battery is getting low
Microlife IR 310
“When the unit is turned on, the icon will keep flashing to remind the user to replace the battery.”
Microlife’s manual keeps this apart from the flat battery below, where the battery icon is the only thing on the screen.
Every make: Low battery symbol. Source: Microlife Ear Thermometer IR 310 — instruction manual (IB IR 310 N-V10, PDF) Checked 2026-10-13.
Battery icon alone The battery is flat
Microlife IR 310
“If only the icon is shown on the display, the battery should be replaced immediately.”
What Microlife says to do: “Replace the batteries – ensure correct polarity as shown by the symbols in the compartment.”
The IR 310 takes 2 AAA batteries. For a blank display, Microlife’s table says to check that the battery is loaded correctly, polarity included.
Every make: Low battery symbol. Source: Microlife Ear Thermometer IR 310 — instruction manual (IB IR 310 N-V10, PDF) Checked 2026-10-13.
M with a number Memory: past readings
Microlife IR 310
“This thermometer can recall the last 30 readings with a record of both time and date.”
“Number 1 and a flashing «M» are displayed.”
Reading 1 is the most recent one; each press of the M-button goes one further back.
Every make: M, memory number or memory icon. Source: Microlife Ear Thermometer IR 310 — instruction manual (IB IR 310 N-V10, PDF) Checked 2026-10-13.
These pages report what each maker’s manual says and quote it wherever health is involved. They do not diagnose anything, they are not medical advice, and they do not tell you whether a temperature is a fever or what to do about it; only your own thermometer’s manual and your doctor or nurse can do that for the person you are looking after.
Other thermometer makers
Sources
Every state above is quoted from these documents on Microlife’s own website, fetched and read on the date shown. Words in quotation marks are Microlife’s; everything else is ours.
- Microlife: Microlife Ear Thermometer IR 310 — instruction manual (IB IR 310 N-V10, PDF) Checked 2026-10-13.
- Microlife: Microlife NC 200 non-contact thermometer — instruction manual (IB NC 200-e N-V10, 2026-08-17, PDF) Checked 2026-10-13.