For: Admins and Managers
Use this article if one or more individual sensors have stopped sending readings while your Hub is working normally.
Note: If you've recently resolved a Hub outage, your sensors may have gone offline or drained their batteries during that period. Work through this article for each affected sensor.
Note: A Corrective Action is created automatically when a sensor stops sending readings. Once the sensor is back online, record what you did on that task. See Managing sensor outages and corrective actions.
Step 1: Check the battery level
The most common cause of a sensor going offline is a flat battery. Before anything else, check this first.
Log in to the Admin Console.
Go to Dashboard > Sensors.
Adjust the date range in the top right corner to cover the period when readings stopped. (e.g. the last 3 months)
In the Sensor Summary, find the affected sensor and check its Last Battery level. Hover over it to see the exact voltage.
If it shows Low, skip straight to Step 2.
If it shows Healthy or Medium, continue to Step 3.
Battery levels are worked out from each sensor type's usable voltage range, so they show how much life is actually left. A Monitor Pro sensor is full at 3.6V and flat at 2.9V. A Monnit sensor is full at 2.8V and flat at 2.0V.
Step 2: Replace the battery
Carefully unscrew the sensor casing.
Note the battery orientation (+/-) before removing it.
Swap the battery with one from a known-working sensor to test.
If the sensor responds with the swapped battery, the original is flat — continue from step 5.
If the sensor is still unresponsive with a known-good battery, it may have an internal fault. Contact [email protected].
Insert a new 3.6V Lithium battery (EVE ER18505 or similar) in the correct orientation. Standard AA alkaline batteries will not work.
Check that the internal switch inside the sensor casing is set to ON — this can accidentally be knocked to OFF during battery changes.
Screw the casing back together securely, ensuring any seals are seated correctly.
Turn on your Sensor by holding down the Power button for 1 second
Check the dashboard — the sensor should reappear within 15 minutes.
Replacement batteries are available from the Safe Food Pro NZ Shop or Safe Food Pro AU Shop.
Note: Battery life is typically 2–3 years, but extreme cold and distance from the Hub can shorten this significantly. Keep an eye on Last Battery in the Sensor Summary and replace the battery when it shows Low. Use the Battery filter to see every sensor with a low battery at once.
Step 3: Run a quick communication test
If the battery is fine, check whether the sensor can communicate with the Hub at all.
Take the sensor and stand next to the Hub.
Press the Power button on the sensor once.
Watch the Hub's RF light:
Blue flash — the sensor is communicating with the Hub. The issue is likely signal strength in its usual location. Skip to Step 4.
No blue flash — the sensor is not reaching the Hub even at close range. Continue to Step 4 and then check signal and placement.
Step 4: Check signal strength and placement
If the battery is confirmed good but the sensor is still offline, signal or placement is the likely cause.
Signal levels: The Sensor Summary shows Last Signal as Good, Fair or Poor. Hover over it to see the reading in dBm. The bands are different for each sensor type, because Monitor Pro sensors keep working at much weaker signals than Monnit sensors.
Signal | Monitor Pro sensors | Monnit sensors |
Good | −120 dBm or stronger | −80 dBm or stronger |
Fair | −121 to −130 dBm | −81 to −110 dBm |
Poor | Weaker than −130 dBm | Weaker than −110 dBm |
Signal is shown in negative numbers, so −60 dBm is stronger than −100 dBm.
Common sources of signal obstruction:
Metal (fridge/freezer walls, stainless steel shelving, large containers)
Thick concrete walls or floors
Water, ice, or densely packed cool rooms
Nearby high-power equipment (microwaves, large electric motors)
Note: If you recently moved this sensor to a new location, reduced signal is the most likely cause. Check Last Signal in the Sensor Summary before working through these steps.
Temporarily move the sensor next to the Hub.
Press the Power button on the sensor to transmit a manual reading immediately.
Check the dashboard after 15–20 minutes — allow up to an hour for a full confirmation.
If readings appear, the original location has a range or obstruction problem — continue from step 5.
If readings still don't appear and the battery is confirmed good, the sensor may be faulty. Contact [email protected].
If the sensor can be repositioned, move it closer to the door, higher up, or away from metal walls and corners. Ensure the antenna is attached and oriented vertically.
If the sensor can't be repositioned, consider moving the Hub closer instead — keep the Hub in the open, away from metal cabinets. A longer Ethernet cable may be required for LAN Hubs (WH-2).
Step 5: Check sensor assignment
If the sensor is communicating with the Hub but still not appearing correctly on the dashboard, it may not be assigned to a piece of equipment.
On the Sensors tab, check the Equipment column for the affected sensor.
If no equipment is listed, navigate to Equipment in the Admin Console.
Locate or create the relevant item of equipment and click to open its profile.
Click the three dots > Edit Technical Details.
Scroll to Sensor Readings and enable Sensor Readings.
Assign the sensor and save your changes.
Check the dashboard after 15 minutes to confirm readings are coming through.
Step 6: Check for physical damage
If nothing above has resolved the issue, inspect the sensor itself.
Inspect the sensor casing for cracks, moisture ingress, or antenna damage.
Unscrew the casing and check inside for battery erosion or corrosion.
Confirm the sensor is within its operating temperature range (-40°C to +125°C). Battery performance degrades significantly below freezing or above 50°C.
If the sensor was recently moved between very different temperatures, allow time for condensation to clear before assuming a fault.
Still having trouble?
If you've worked through these steps and the issue isn't resolved, contact [email protected].
To help us diagnose the issue faster, include:
Your business name
Sensor ID/Name
Last Reading, Last Battery and Last Signal from the Sensor Summary, including the voltage and dBm shown when you hover over them
The sensor's location (e.g. walk-in freezer, back wall, near stainless steel shelving)
Approximate time the issue started
Troubleshooting steps already tried