# How to check flow cell vacuum pressure on the NovaSeq 6000
**Background**
The NovaSeq Service Software (NVSS) can be used to check the vacuum pressure when the instrument or flow cell is the suspected cause of a vacuum issue.
* See also [How to resolve Vacuum Failure Phenotype and "Flow cell Vacuum is no longer engaged" on NovaSeq 6000](/instrumentation/novaseq-6000/instrumentation-novaseq-6000-troubleshooting-list/000001309.md).
**To check the flow cell vacuum pressure:**
* Close the NovaSeq Control Software and launch NovaSeq Service Software (NVSS).
* Once initialized, select the **Flow Cell** option on main screen.
* Load wash flow cells on Sides A and B.
* Pressure readings for the wash flow cell should be around -90 kPa and show a steady green check mark for the sensor.
* If the pressure is low or the sensor is not steady, clean the flow cell and stage, and re-check pressure values.
* If the vacuum pressure is within the expected range, perform a power cycle on the instrument and proceed with next run. See [How to Power Cycle the NovaSeq 6000 System](/instrumentation/novaseq-6000/instrumentation-novaseq-6000-reference_material-list/000002470.md).
* If vacuum pressure is not within expected range, contact [Illumina Technical Support](https://www.illumina.com/company/contact-us.html#/united-states/technical-support).
**NovaSeq 6000 Control software v1.8** introduced an option to check vacuum pressure prior to run start. This can be done through the control software.
**To check the flow cell vacuum pressure from NovaSeq control software v1.8 and above:**
* Open the NovaSeq Control Software (NVCS).
* Select **Tools** from the dropdown menu on the upper left corner.
* Select **Flow Cell Vacuum**.
* Load wash flow cells on sides A and B.
* Pressure readings for the wash flow cell should be around -90 kPa and show a steady green check mark for the sensor.
\
\
\
| |
| :--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------: |
| *For any feedback or questions regarding this article (Illumina Knowledge Article #5390), contact Illumina Technical Support* [*techsupport@illumina.com*](mailto:techsupport@illumina.com?subject=Question%2FFeedback%20Regarding%20Illumina%20Knowledge%20Article%20#000002470%20-%20Instrumentation%20\&body=Dear%20Illumina%20Technical%20Support,%0D%0A%0D%0A)*.* |
---
# Agent Instructions: Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.
Perform an HTTP GET request on the current page URL with the `ask` query parameter:
```
GET https://knowledge.illumina.com/instrumentation/novaseq-6000/instrumentation-novaseq-6000-reference_material-list/000005390.md?ask=
```
The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.
Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.