> 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/000002492.md).

# How to troubleshoot failed Pressure Decay or Impedance tests on the NovaSeq 6000

**Background** The Pressure Decay and Impedance tests on the NovaSeq 6000 rely on pressure sensors for accurate readings during these checks. The Pressure Decay test dries out the system, and issues with the pressure sensors can result in inaccurate or incomplete results, causing this test to stop or fail. In this scenario, the Impedance test fails as a consequence of the system not being fully primed with liquid after Pressure Decay failure. If Pressure Decay or Impedance tests on the NovaSeq 6000 system check fail or stop with NaN result, see the following instructions to check the pressure sensor readings and provide them to [Technical Support](https://www.illumina.com/company/contact-us.html#/united-states/technical-support).

1. Close NovaSeq Control Software, then open the **NovaSeq Service Software** (NVSS).
2. Select **Integrated Chassis Assembly** (Figure 1).
3. Navigate to the Sensors Tab and select the **refresh icon** under the **Fluidics** header (Figure 1).
4. If any sensor is > 3.5 psi, take a screenshot or picture of the result and collect NovaSeq Service Software Logs located under C:\ProgramData\Illumina\NovaSeq\NovaSeq Service Software\Logs
5. Once the screenshot and logs are collected, contact [Illumina Technical Support](https://www.illumina.com/company/contact-us.html#/united-states/technical-support) for the next steps.

**Important Note**: Pressure sensors are not used during a run and failing sensors will not impact a run performance. The instrument can continue sequencing until an Illumina Field Service Engineer (FSE) can replace the sensors.

![](/files/SPbIYN7sM1JvgyOt1nD5)

**Figure 1.** Location of the Sensors tab in the Integrated Chassis Assembly of the NVSS.

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| *For any feedback or questions regarding this article (Illumina Knowledge Article #2492), contact Illumina Technical Support* [*techsupport@illumina.com*](mailto:techsupport@illumina.com?subject=Question%2FFeedback%20Regarding%20Illumina%20Knowledge%20Article%20#000002492%20-%20Instrumentation%20\&body=Dear%20Illumina%20Technical%20Support,%0D%0A%0D%0A)*.* |


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