Sensor Not Connecting to Gateway

If a Sensor is not connecting to its Gateway

If a sensor requires repair, best-effort troubleshooting steps must be taken before the Return Material Authorization form (RMA) is issued when returning a device to Monnit for diagnosis and/or repair.

When a sensor will not connect to a gateway:

All Monnit sensors, except for Monnit MoWi (WiFi) sensors, require a gateway. The gateway acts as a relay, transmitting the data from the sensors to the data endpoint, which is generally Understanding the role of the gateway is crucial when troubleshooting communication issues. 

You may find that your Monnit Commercial or Alta sensor is unable to communicate with its corresponding gateway (when first setting up or after it has already been communicating). If you encounter this issue, please follow the steps below to diagnose and troubleshoot it.

Summary of Steps

  • Check compatibility of sensor/gateway.
  • Confirm the gateway and sensor have been added to the same sensor network.
  • Confirm the Network is not configured to be a Holding Network.
  • Confirm the gateway is checking in.
  • Through the iMonnit Online Portal, reset the sensor to the Default settings using the gray Default button under the Settings tab in the iMonnit Online Portal.
  • Press and immediately release the Utility/Reset button on the gateway once (to download sensor ID’s).
  • Examine the sensor for damage or signs of liquid ingress and corrosion.
  • Eliminate environmental variables by placing the sensor 10-15 feet from the gateway line of sight when possible (the sensor should not be tested closer than the minimum distance of 10 feet).
  • Power the sensor off for at least 60 seconds (for sensors without a switch, remove the batteries).
  • Swap the batteries with another sensor that is already checking in or insert known-good batteries. (If you have an Industrial model, please refrain from opening the enclosure as this may void the warranty.)
  • Press and immediately release the button on the gateway.

Check compatibility of your devices.

Monnit offers two generations of wireless sensors (in addition to the MoWi WiFi sensors). These two generations offer different hardware that is not compatible between generations. Therefore, if you have Gen1 sensors, you will need a Monnit Commercial (often referred to as Gen1) gateway. Likewise, you will need an Alta gateway if you have Alta sensors. 

Additionally, the radios of these products operate in several frequency bands. For example, in the U.S., sensors use the sub-gigahertz unlicensed 900 MHz band. For your sensors to communicate with gateways, you must be sure the sensor and gateway operate in the same band. Monnit generally offers 900 MHz, 868 MHz, and 433 MHz sensors.

To view the hardware configuration of a sensor or gateway, you can visit site, enter the device ID and Security Code, and you will see the hardware configuration for the device.

Confirm the gateway and sensor have been added to the same sensor network.

A gateway must retrieve a sensor ID to it’s Sensor List to authorize communication. The gateway receives the ID of a sensor to its Sensor List after the sensor and gateway have been added to the same network (in iMonnit for example), and the gateway performs the operation of downloading the ID of that sensor from the software network. The operation of the gateway downloading the sensor ID’s from the software network occurs in three scenarios:

  1. When the gateway is first powered up
  2. When the Utility button is pressed and immediately released (initiating an immediate manual check in)
  3. When the network of the gateway is Reformed.

If a sensor is powered up after the gateway has downloaded the sensor IDs from the software network, it will be authorized to communicate with the gateway. This is why powering the sensor off, pressing and immediately releasing the button on the gateway (so the gateway downloads the sensor IDs from the software network), and then powering the sensor up, will often resolve connection issues.

Confirm the gateway is checking in

Check the LED’s on the gateway (for gateways that have LED indicators) and iMonnit software to confirm that your gateway is currently checking in. If you do not see data from the gateway, review one of the following articles.

Ethernet Gateway 4 Not Connecting

Monnit 4G LTE Gateway Not Connecting (customer’s own data plan)

Monnit 4G LTE Gateway Not Connecting (data plan through Monnit)

Examine the sensor for damage or signs of liquid ingress and corrosion

The sensors should be examined for damage or liquid ingress and corrosion. For sensors with removable batteries, the sensor’s circuitry should be examined for corrosion. The antenna and probe should be observed with a firm connection to the sensor circuitry.

Eliminate environmental variables.

The most common causes of a sensor being unable to communicate with its gateway are due to environmental factors. Therefore, it's crucial to eliminate these variables, staying focused and determined in your troubleshooting efforts.

The most effective way of doing this is to remove the sensor from any installation (if possible, and especially if the sensor is near machinery or other sources of EMI, such as voltage/current), place the sensor 10-15 feet from the gateway, and test the sensor with a known-good battery.

Confirm the sensor is using a known-good battery

Monnit does not recommend opening the enclosure of Monnit Industrial-type sensors as this may void the warranty of the sensor. Be advised, the following information is intended for coin cell and AA sensors.

Since Monnit sensors are battery-operated, you will need to confirm that the battery powering your sensor is good. The most effective way to do this is to swap the battery from one sensor that is already checking in as expected with a sensor that is not checking in.

This will confirm the battery's state, leaving the sensor not checking in, and confirm you are using a known-good battery replacement. If you do not have additional sensors operating from which you can take the battery, the next best thing is testing with a brand-new battery.

Press and immediately release the button on the gateway.

After inserting known-good batteries, press and immediately release the button on your gateway (assuming your gateway type has a user-accessible button). 

If using the Monnit Link USB Gateway, you can click the button in the Monnit Link Gateway Utility that says, "Send Messages to Server." This will initiate an immediate check-in with the iMonnit server, thereby uploading any communications with the sensor.


If after completing the steps above the sensor does not communicate, you will want to contact Monnit Support for additional review.

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