> Source: [sk101898](https://support.checkpoint.com/results/sk/sk101898)

# sk101898 - "The value of sensor could not be read" error in /var/log/messages file and SNMP Traps about hardware sensors are sent repeatedly

| Property | Value |
|----------|-------|
| Solution ID | sk101898 |
| Date Created | 2014-08-03 |
| Last Modified | 2026-07-12 |
| Technical Level | Advanced |
| Products | Security Gateway, Security Management Server, Multi-Domain Security Management Server |
| Versions | R82.10, R82, R81.20, R82.10, R82, R81.20, R82.10, R82.20, R81.20, R82, R82.20 |
| OS | Gaia |

## Symptoms

- * `/var/log/messages` file on Gaia OS repeatedly shows:

  * `
    xpand[`*PID* `]: The value of sensor could not be read
    last message repeated `*N*` times 
    `

  * `snmpd: The value of sensor could not be read`

* `trapd.log` file on HP OpenView Network Node Manager Server shows that the following SNMP Traps were sent from the machine at the same time when the sensor errors were printed in the `/var/log/messages` file:

  * `fanFailure;`*N*` .1.3.6.1.4.1.2620.1.3000.5.2.1 0`
  * `voltageChange;`*N*` .1.3.6.1.4.1.2620.1.3000.5.3.1 0`
* Traffic capture on Gaia OS shows that the following SNMP Traps are sent:

  * `Fan sensor system Fan `*N*` : Speed is NotValid, should be `*XXX* `-`*YYY*
  * `Voltage sensor '`*SENSOR_NAME* `': voltage is NotValid, should be over `*ZZZ*

## Cause

By design, SNMP Traps are sent when:

* The value of a sensor could not be read
* The value returned by sensor is 0

In this case, SNMP Traps are sent due to incorrect validation of the values returned by sensors.

## Solution

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