Thermometer or temperature message (too hot or too cold to test)

The meter, or the room it is in, is outside the temperature range in which the maker says a test is accurate. Most meters refuse to test until it warms up or cools down; the FreeStyle Freedom Lite tests anyway and marks the result with a thermometer.

Check your meter’s manual — makers differ.

What it is for

Move the meter and the strips somewhere within the operating range and wait before testing again. The Contour guide (Ascensia) says to “Test in 20 minutes”; the Accu-Chek Guide page (Roche) adds “Do not artificially heat or cool the meter.”

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 never tell you how to treat a result; only your own meter’s manual and your healthcare team can do that for your model.

What it looks like: A small thermometer beside the result on the FreeStyle Freedom Lite; a numbered code on Accu-Chek and Contour meters; HI.t or LO.t on the OneTouch Verio Flex; a written message on the OneTouch Verio Reflect.
Names makers use: Thermometer symbol (FreeStyle); E-8 (Accu-Chek Guide); E27 Too Cold to Test, E28 Too Hot to Test (Contour); HI.t and LO.t (OneTouch Verio Flex); Temperature too high / too low (OneTouch Verio Reflect)

Where makes differ

The operating range is not the same: the FreeStyle Freedom Lite booklet (Abbott) gives 4 °C to 40 °C (40 °F to 104 °F), the Contour Next One guide (Ascensia) 41°F–113°F, the OneTouch Verio Flex booklet (LifeScan) 50-104°F and the OneTouch Verio Reflect booklet 43-111°F. Only FreeStyle still gives a number: Abbott’s booklet says a result with the thermometer “was taken outside of the meter’s specified operating temperature range and may not be accurate” and is still included in the 7-, 14- and 30-day averages. Contour has separate codes for control solution (E24, E25), whose range is narrower. The Accu-Chek Guide refers you to the test strip package insert for the range.

What it does not mean

It is not the thermometer printed on the strip vial or box, which gives the storage temperature limits (see the temperature-limit page). HI.t and LO.t on a OneTouch Verio Flex are not glucose results: LifeScan’s booklet says HI.t means the meter is “too hot (above 104°F) to perform a test” and LO.t “too cold (below 50°F)”.

Other symbols with the same shapes

HI on the meter (above the measuring range)The letters HI where the number would be, sometimes flashing with…LO on the meter (below the measuring range)The letters LO where the number would be, sometimes flashing with…Error code (E-1, E 1, Error 1)The letter E, or the word Error, with a number, shown instead of a…Memory and averages (mem, avg, logbook)The letters mem, or davg with a number of days, on the FreeStyle…

Sources

No published standard we could check defines blood glucose meter control icons, so this meaning is taken from 4 makers’ own manuals and support pages, each fetched and read on the date shown:

Abbott: FreeStyle Freedom Lite blood glucose monitoring system — owner’s booklet (Australia, ART22410-102 Rev. B, PDF) — Meter display: “Thermometer Symbol — Appears if your meter is out of operating temperature range”; Test Results: a result with a thermometer symbol “may not be accurate. This value is included in your 7-, 14- and 30-day averages”; Operating Temperature 4 °C to 40 °C. Checked 2026-09-28.
Roche: Accu-Chek — Guide meter error codes (support pages for E-1 to E-14, HI, LO and the battery icon) — E-8: “The temperature is above or below the proper range for the system … Move to an area with the appropriate conditions and repeat the blood glucose or control test. Do not artificially heat or cool the meter.” Checked 2026-09-28.
Ascensia: CONTOUR NEXT ONE blood glucose monitoring system — user guide (US, PDF) — Meter Operating Temperature Range 41°F–113°F; E24 Too Cold to Test Control Solution, E25 Too Hot, E27 Too Cold to Test, E28 Too Hot to Test: “Move the meter and strip to a warmer area. Test in 20 minutes.” Checked 2026-09-28.
LifeScan: OneTouch Verio Flex — owner’s booklet (US, PDF) — Troubleshooting: HI.t “Meter is too hot (above 104°F) to perform a test”, LO.t “Meter is too cold (below 50°F)”; operating range 50-104°F. Checked 2026-09-28.
LifeScan: OneTouch Verio Reflect — owner’s booklet (US, PDF) — Troubleshooting: “Temperature too high. Out of operating range.” (above 111°F) and “Temperature too low” (below 43°F); operating range 43-111°F. Checked 2026-09-28.

Written in our own words; quotations are the makers’ wording.