> 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/sample-gives-an-error.md).
# Sample gives an error
Clean and try again. If the error comes back, run a QC test.
When a sample gives an error, the cause is either in the sample or in your BactoBox®. A QC test tells the two apart, because it measures a vial with a known content.
## What to do
{% stepper %}
{% step %}
#### Clean and try again
Run [Clean](/more/how-to-guides/clean-your-setup.md) with a fresh SBT [disinfection vial](/item-register/consumables/disinfection-vial.md). Make a new sample vial and measure it.
An error can happen once, for example because of an air bubble. If the error does not come back, carry on.
{% endstep %}
{% step %}
#### Check how you prepared the sample
Some errors point to the sample. Look up your code in [Errors a sample can cause](#errors-a-sample-can-cause) below, and fix the sample before you go on.
Use SBT consumables to prepare your samples. They rule out many errors that are very hard for us to trace in a sample. See [Check your consumables](/troubleshooting/qc-test-fails/check-your-consumables.md).
{% endstep %}
{% step %}
#### Run a QC test
Error still there? [Run a QC test](/maintenance/qc-test/run-qc-test.md) with SBT consumables only. Then the result tells you about your BactoBox®, not about your vials.
* **QC test passes.** Your BactoBox® works, and the cause is in the sample. Read [Before you measure](/everyday-use/before-you-measure.md). If the error keeps coming back, [contact support](/troubleshooting/contact-support.md). We help you find the cause.
* **QC test fails.** Go to [QC test fails](/troubleshooting/qc-test-fails.md).
{% endstep %}
{% endstepper %}
## Errors a sample can cause
| Codes | Why it happens | What to do |
| ------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| 1201, 1205
Conductivity is too high
| Your BactoBox® measures in a liquid with a set conductivity. Warm dilution liquid conducts more. So does leftover growth medium when you dilute only 1:10, or 1:100 for some media. | Make sure your dilution liquid is at room temperature, not warm. Then dilute more, for example 1:1 000. If the error goes away, the growth medium is raising the conductivity too much for a 1:100 dilution. |
| 1200, 1206
Conductivity is too low
| The liquid conducts too little. Cold dilution liquid, or a liquid that is not SBT dilution liquid, can cause it. So can an air bubble at the conductivity sensor. | Clean and try again. Use SBT dilution liquid at room temperature. |
| 2000–2030
Flow errors
| A sample with many particles can disturb the flow through the flow cell. | If your sample holds many particles, dilute it more. Then clean and try again. |
| 3000
Particle concentration is too high
| The vial is too concentrated for your BactoBox® to measure accurately. | Dilute more. Then clean and try again. See [Hit the right concentration](/more/how-to-guides/hit-the-right-concentration.md). |
For any other code, follow the *During a sample* column in [Error codes](/troubleshooting/error-codes.md).
{% hint style="info" %}
### No error, but the result looks wrong?
Read [Before you measure](/everyday-use/before-you-measure.md). It covers the five mistakes we see most often.
{% endhint %}
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