Honeywell CO2 Duct Sensor

[Macreedy]

I installed 4 of these Honeywell C7232B1006 duct mounted sensors on four package rooftops. I have them set up in analog mode to modulate the economizer damper. The installation is about 10 years old and just clean the sampling tubes every year as they get clogged with dust.

Today, I noticed two of the sensors display a wrench icon and read 0 PPM. I downloaded the latest Honeywell literature, but it doesn't mention any errors, codes, or what to check.

Anyone have information or are these things pretty much disposable?

This is a link to the Honeywell page of the sensor:

https://customer.honeywell.com/en-US...d=C7232B1006/U