> 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.md).

# QC test fails

Follow the steps for your error code. Use fresh SBT vials every time you try again.

The QC test checks that your BactoBox® measures correctly. Fix a failing QC test before you measure samples, because you cannot trust a result from a BactoBox® that fails it.

When the QC test fails, the program goes back to the *Clean* step.

## Before you try again

* **Use SBT consumables only.** Run the QC test with an SBT QC vial, an SBT ready-made dilution vial and an SBT disinfection vial. Then the result tells you about your BactoBox®, not about your vials.
* **Use a fresh QC vial and a fresh dilution vial every time.** Both are for single use only.
* **Use vials at room temperature.** Warm or cold liquid changes the conductivity.
* **Clean with a fresh SBT disinfection vial.** This rules out the cleaning step as the cause.

## Find your error code

Look up the code in [Error codes](/troubleshooting/error-codes.md) and follow the *During a QC test* column in order. Most codes lead to one of these steps.

<table data-view="cards"><thead><tr><th></th><th></th><th data-hidden data-card-target data-type="content-ref"></th></tr></thead><tbody><tr><td><strong>Check your consumables</strong></td><td>Check the target concentration and your vials.</td><td><a href="/troubleshooting/qc-test-fails/check-your-consumables.md">Check your consumables</a></td></tr><tr><td><strong>Check the flow cell</strong></td><td>Look for liquid, then try a new flow cell.</td><td><a href="/troubleshooting/qc-test-fails/check-the-flow-cell.md">Check the flow cell</a></td></tr><tr><td><strong>Recover a flow cell</strong></td><td>Deep clean a flow cell that failed.</td><td><a href="/troubleshooting/qc-test-fails/recover-a-flow-cell.md">Recover a flow cell</a></td></tr><tr><td><strong>Check liquid uptake</strong></td><td>Make sure liquid flows into your BactoBox®.</td><td><a href="/troubleshooting/qc-test-fails/check-liquid-uptake.md">Check liquid uptake</a></td></tr></tbody></table>

## Still failing?

[Contact support](/troubleshooting/contact-support.md). Tell us the error code and the steps you tried. We want to know when a QC test keeps failing.


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