> For the complete documentation index, see [llms.txt](https://help.sbtinstruments.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.sbtinstruments.com/troubleshooting/qc-test-fails/check-the-flow-cell.md).

# Check the flow cell

Look for liquid under the flow cell. Then try a new flow cell and external filter.

A QC test error can come from the flow cell, or from how your samples have affected the flow cell. A new flow cell tells you if the old one is the cause.

## Get things ready

You need these items:

* 1 × new [flow cell](/item-register/consumables/flow-cell.md)
* 1 × new [external filter](/item-register/individual-items/external-filter.md). Every flow cell ships with two.
* Everything you need to [run a QC test](/maintenance/qc-test/run-qc-test.md)

{% hint style="info" %}
A QC test does not use any of the 250 measurements on a flow cell.
{% endhint %}

## Step by step

{% stepper %}
{% step %}

#### Clean

Run [Clean](/more/how-to-guides/clean-your-setup.md) before you remove the flow cell.
{% endstep %}

{% step %}

#### Remove the flow cell

Remove the flow cell cover. Press the clamps together and lift the flow cell out. Keep it, so you can try to [recover it](/troubleshooting/qc-test-fails/recover-a-flow-cell.md) later.
{% endstep %}

{% step %}

#### Look for liquid

Look into the flow cell compartment for liquid or drops.

{% hint style="danger" %}

### Found liquid? Stop here

Switch off your BactoBox®. Do not insert a flow cell. [Contact support](/troubleshooting/contact-support.md), and send a photo of the flow cell compartment.
{% endhint %}
{% endstep %}

{% step %}

#### Install a new flow cell and external filter

[Install the new flow cell](/getting-started/installation/install-flow-cell.md). Then replace the external filter, as shown in [Install tubing kit](/getting-started/installation/install-tubing-kit.md).
{% endstep %}

{% step %}

#### Run a QC test

[Run a QC test](/maintenance/qc-test/run-qc-test.md) with fresh vials.

* **QC test passes.** The old flow cell was the cause. Keep using the new one. When you have time, try to [recover the old flow cell](/troubleshooting/qc-test-fails/recover-a-flow-cell.md).
* **QC test fails.** [Contact support](/troubleshooting/contact-support.md).
  {% endstep %}
  {% endstepper %}

{% hint style="info" %}

### After error 1000, do not try to recover the old flow cell

A deep clean does not fix error 1000. If the old flow cell is still under warranty, [contact support](/troubleshooting/contact-support.md). See the warranty on the [flow cell](/item-register/consumables/flow-cell.md) page.
{% endhint %}


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