# Sensor A is downgraded, but Sensor B is stuck at zero

**URL:** <https://community.purpleair.com/t/sensor-a-is-downgraded-but-sensor-b-is-stuck-at-zero/21943>\
**Category:** Sensors\
**Created:** [July 29, 2025, 2:34am UTC](https://community.purpleair.com/t/sensor-a-is-downgraded-but-sensor-b-is-stuck-at-zero/21943 "2025-07-29T02:34:56Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![Gordon](https://avatars.discourse-cdn.com/v4/letter/g/3da27b/32.png) [@Gordon](https://community.purpleair.com/u/Gordon)\
**Post date:** [July 29, 2025, 2:34am UTC](https://community.purpleair.com/t/sensor-a-is-downgraded-but-sensor-b-is-stuck-at-zero/21943/1 "2025-07-29T02:34:57Z")

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![image](https://us1.discourse-cdn.com/flex020/uploads/purpleair/original/2X/2/20857c298185fd78a39d91dbf173179885c57cc4.png)

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**Author:** ![Kieran](https://sea2.discourse-cdn.com/flex020/user_avatar/community.purpleair.com/kieran/32/6220_2.png) [@Kieran](https://community.purpleair.com/u/Kieran)\
**Post date:** [July 29, 2025, 5:24pm UTC](https://community.purpleair.com/t/sensor-a-is-downgraded-but-sensor-b-is-stuck-at-zero/21943/2 "2025-07-29T17:24:13Z")

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Hi @Gordon

Thanks for letting us know. This is a mistake that our system can make when automatically downgrading channels. I’ve gone ahead and switched those downgrades around, so now channel B is downgraded. If this is your sensor and you’re interested in troubleshooting, you can reach out to us at [contact@purpleair.com](mailto:contact@purpleair.com).

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**Author:** ![Gordon](https://avatars.discourse-cdn.com/v4/letter/g/3da27b/32.png) [@Gordon](https://community.purpleair.com/u/Gordon)\
**Post date:** [July 29, 2025, 8:29pm UTC](https://community.purpleair.com/t/sensor-a-is-downgraded-but-sensor-b-is-stuck-at-zero/21943/3 "2025-07-29T20:29:14Z")

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Hi Kieran

Thanks for the prompt action and response. It is my sensor. I’m at another location now, but I will be back at South Fork next week, and will check for any obvious problems.

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**Author:** ![Gordon](https://avatars.discourse-cdn.com/v4/letter/g/3da27b/32.png) [@Gordon](https://community.purpleair.com/u/Gordon)\
**Post date:** [September 1, 2025, 12:31am UTC](https://community.purpleair.com/t/sensor-a-is-downgraded-but-sensor-b-is-stuck-at-zero/21943/4 "2025-09-01T00:31:27Z")

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Shop vac and canned “air” did not help. But after opening sensor and scraping out a dense spider web, on August 29, Sensor B is now working again. Can you reset Sensor B downgrade? Thanks.

 ![image](https://us1.discourse-cdn.com/flex020/uploads/purpleair/original/2X/b/b5519df06377c0c57a818918db2bb25f3ebac84e.png)

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**Author:** ![Kieran](https://sea2.discourse-cdn.com/flex020/user_avatar/community.purpleair.com/kieran/32/6220_2.png) [@Kieran](https://community.purpleair.com/u/Kieran)\
**Post date:** [September 3, 2025, 5:09pm UTC](https://community.purpleair.com/t/sensor-a-is-downgraded-but-sensor-b-is-stuck-at-zero/21943/5 "2025-09-03T17:09:40Z")

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Hi @Gordon

Thanks for letting us know. I’ve gone ahead and removed the downgrade on Channel B.

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**Author:** ![Gordon](https://avatars.discourse-cdn.com/v4/letter/g/3da27b/32.png) [@Gordon](https://community.purpleair.com/u/Gordon)\
**Post date:** [July 15, 2026, 10:08pm UTC](https://community.purpleair.com/t/sensor-a-is-downgraded-but-sensor-b-is-stuck-at-zero/21943/6 "2026-07-15T22:08:04Z")

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This time channel B is downgraded, but channel A is stuck at 0, and B is ok.