> For the complete documentation index, see [llms.txt](https://knowledge.illumina.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://knowledge.illumina.com/instrumentation/novaseq-6000/instrumentation-novaseq-6000-troubleshooting-list/000002523.md).

# How to troubleshoot failed to reach target temperature error on the NovaSeq 6000

During a sequencing run, the NovaSeq 6000 Control Software can report the error:

**Error message:**\
"The flow cell is unable to reach the target temperature. The run is proceeding, but contact Illumina Technical Support for help."

This error does NOT stop the sequencing run. Normally, there is very little to no impact to run performance or quality post error message. The possible causes for this error are:

* Transient communication issue.
* An issue with the instrument flow cell heater.

**Troubleshooting steps:**

1. Power cycle the instrument.

* For additional details on power cycle, see the Knowledge Base article [How to Power Cycle the NovaSeq 6000 System.](/instrumentation/general/instrumentation-general-reference_material-list/000002470.md)

2. Perform only Thermal - Automated Tests and Misc - Sensor Status Readouts tests in System Checks.

* For additional details on system check, search for Knowledge Base article [How to perform system checks on the NovaSeq 6000.](/instrumentation/novaseq-6000/instrumentation-novaseq-6000-reference_material-list/000002495.md)

3. If system check results pass, proceed with the next run.
4. If either test on the system check fails or the error reoccurs on the next run, 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 #2523), contact Illumina Technical Support* [*techsupport@illumina.com*](mailto:techsupport@illumina.com?subject=Question%2FFeedback%20Regarding%20Illumina%20Knowledge%20Article%20#000002495%20-%20Instrumentation%20\&body=Dear%20Illumina%20Technical%20Support,%0D%0A%0D%0A)*.* |


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