Mobi thermometer screen: what LO, HI, ErrE, FOOD and the house icon mean
Mobi’s instruction manual for the DualScan Prime ear and forehead thermometer (item 70121) names every state below. Each one has Mobi’s own words in quotation marks, what Mobi says to do, and a link to our page on the same symbol across other makes.
Check your thermometer’s manual — makers differ.
All 10 Mobi screen states at a glance
| On the screen | What Mobi’s manual says it means |
|---|---|
LO | Below the range it reports — not a battery warning |
HI | Above the range it reports |
ErrE | An error Mobi fixes by warming the thermometer |
Low battery indicator | Time to replace the batteries |
FOOD | Liquid and food mode, not a body reading |
House icon | Room temperature |
Flashing ear icon | Wait before the next ear reading |
Ear or forehead symbol beside a stored reading | Memory, and where each reading was taken |
12hr or 24hr flashing | Time, date and sleep-mode settings |
°F or °C | The temperature scale |
Which models this covers
Mobi publishes a separate manual for each thermometer on its user-manuals page; the one read here is the DualScan Prime (item 70121). Other Mobi models, such as the talking DualScan or the non-contact Air thermometers, have their own manuals, and their screens may differ.
Each state, in Mobi’s words
LO Below the range it reports — not a battery warning
“‘LO’ is displayed for result below 89.6 °F (32.0 °C).”
“The ‘LO’ reading does not reflect the battery level.”
What Mobi says to do: “Please ensure that you are in correct reading method.”
Mobi’s manual also says: “If display shows HI/LO please make sure thermometer is in the correct ‘FOOD’ setting.” Mobi’s own fixes for LO are about how the reading was taken: the right reading method and the right mode.
Every make: Lo on a thermometer. Source: Mobi DualScan Prime Ear & Forehead Thermometer, item 70121 — instruction manual (PDF, from Mobi’s user-manuals page) Checked 2026-10-13.
HI Above the range it reports
“‘HI’ is displayed for all results above 109.3 °F (42.9 °C).”
What Mobi says to do: “Please ensure that you are in correct reading method.”
Mobi gives the same range for ear and forehead: 89.6 °F to 109.3 °F (32.0 °C to 42.9 °C).
Every make: Hi on a thermometer. Source: Mobi DualScan Prime Ear & Forehead Thermometer, item 70121 — instruction manual (PDF, from Mobi’s user-manuals page) Checked 2026-10-13.
ErrE An error Mobi fixes by warming the thermometer
“If you receive and ‘ErrE’ message on the screen, place the thermometer in a warm place and let sit for 30 minutes.”
What Mobi says to do: “To reset your thermometer, take out the batteries for 1 hour while storing the unit in a warm place.”
Mobi also says to keep the sensor out of direct sunlight while it rests.
Every make: Err or Er with a number. Source: Mobi DualScan Prime Ear & Forehead Thermometer, item 70121 — instruction manual (PDF, from Mobi’s user-manuals page) Checked 2026-10-13.
Low battery indicator Time to replace the batteries
“Replace battery when low battery indicator appears.”
What Mobi says to do: “When replacing batteries, always replace with new AAA batteries.”
If it does not switch on after new batteries, Mobi says to take them out, wait 60 seconds and put them back.
Every make: Low battery symbol. Source: Mobi DualScan Prime Ear & Forehead Thermometer, item 70121 — instruction manual (PDF, from Mobi’s user-manuals page) Checked 2026-10-13.
FOOD Liquid and food mode, not a body reading
“Press both the ‘HEAD & EAR’ buttons at the same time until ‘FOOD’ is displayed on the screen.”
What Mobi says to do: “Hold the thermometer approximately 1 Inch away from the object surface. Then press and release the ‘EAR’ button to take the reading.”
If FOOD is showing when you take a person’s temperature, the number is not a body temperature.
Every make: Body, forehead, object or room mode symbol. Source: Mobi DualScan Prime Ear & Forehead Thermometer, item 70121 — instruction manual (PDF, from Mobi’s user-manuals page) Checked 2026-10-13.
House icon Room temperature
“When the thermometer is turned on, the thermometer will display the ambient room temperature. The icon of the house will be present on the bottom right side of the thermometer screen.”
The number beside the house icon is the room, not the person.
Every make: Body, forehead, object or room mode symbol. Source: Mobi DualScan Prime Ear & Forehead Thermometer, item 70121 — instruction manual (PDF, from Mobi’s user-manuals page) Checked 2026-10-13.
Flashing ear icon Wait before the next ear reading
“Please allow 6 seconds before the next reading. The ear icon will stop flashing on the display.”
Start the next ear reading once the ear icon is steady.
Every make: Flashing °C, °F or mode symbol. Source: Mobi DualScan Prime Ear & Forehead Thermometer, item 70121 — instruction manual (PDF, from Mobi’s user-manuals page) Checked 2026-10-13.
Ear or forehead symbol beside a stored reading Memory, and where each reading was taken
“This thermometer can recall up to 9 prior measurements.”
“The symbols for ear or forehead will appear with each measurement stored in memory to indicate whether a person’s forehead or ear temperature was taken.”
Each press of the MEM button goes back one reading.
Every make: M, memory number or memory icon. Source: Mobi DualScan Prime Ear & Forehead Thermometer, item 70121 — instruction manual (PDF, from Mobi’s user-manuals page) Checked 2026-10-13.
12hr or 24hr flashing Time, date and sleep-mode settings
“Press and hold the ‘SET’ button to enter the settings mode. There will be a 12hr or 24hr flashing on the screen.”
MEM changes the flashing option and SET moves on, through time format, hour, minute, year, month, day and sleep mode.
Source: Mobi DualScan Prime Ear & Forehead Thermometer, item 70121 — instruction manual (PDF, from Mobi’s user-manuals page) Checked 2026-10-13.
°F or °C The temperature scale
“When thermometer is in measuring or memory mode, press and hold the ‘SET’ button to switch between °F and °C.”
The same button held down from the time screen opens the settings instead.
Every make: °C or °F on the display. Source: Mobi DualScan Prime Ear & Forehead Thermometer, item 70121 — instruction manual (PDF, from Mobi’s user-manuals page) 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 Mobi’s own website, fetched and read on the date shown. Words in quotation marks are Mobi’s; everything else is ours.
- Mobi: Mobi DualScan Prime Ear & Forehead Thermometer, item 70121 — instruction manual (PDF, from Mobi’s user-manuals page) Checked 2026-10-13.
- Mobi: Mobi user manuals page (lists the DualScan Prime manual above) Checked 2026-10-13.