# How to troubleshoot Reagent Selector Valve Errors on the NovaSeq 6000

Reagent Selector Valve errors can be caused either due to a transient instrument communication issue or an instrument hardware related issue.\* Run stopping error messages:

* "The software has exceeded three attempts to correct a problem with the reagent selector valve, and cannot save the flow cell. Call Technical Support for help."
* "The software has exceeded three attempts to correct a problem with the reagent selector valve and must end the sequencing run. Call Technical Support for help."

To troubleshoot this type of error:

* Power cycle the instrument. For more information on the power cycle, search for Knowledge Base article **How to Power Cycle the NovaSeq 6000 System?**
* Perform Valve Control test under Fluidics system check **5 times.**
  * For more information on system check, search for Knowledge Base article **How to perform system check the NovaSeq 6000 System?**
  * If any of the 5 system check for these tests **fail**, [contact Illumina Technical Support](https://www.illumina.com/company/contact-us.html#/united-states/technical-support) with system check results for the next steps.
  * If all tests **pass**, perform a wash and monitor for any valve error on the next run.
  * If the next run fails with the same error, [contact Illumina Technical Support](https://www.illumina.com/company/contact-us.html#/united-states/technical-support).

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| *For any feedback or questions regarding this article (Illumina Knowledge Article #1302), contact Illumina Technical Support* [*techsupport@illumina.com*](mailto:techsupport@illumina.com?subject=Question%2FFeedback%20Regarding%20Illumina%20Knowledge%20Article%20#000001302%20-%20Instrumentation%20\&body=Dear%20Illumina%20Technical%20Support,%0D%0A%0D%0A)*.* |


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