> 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/more/service-and-support/check-engine-light.md).
# Check engine light
Like the one in your car, the check engine light tells you it is time for preventive maintenance.
The check engine light tells you that your BactoBox® is due for [preventive maintenance](/more/service-and-support/annual-preventive-maintenance.md). It appears in the upper right corner of the screen ([Dash](/software/dash/user-interface.md)).
{% hint style="success" %}
When the check engine light appears, schedule preventive maintenance as soon as possible. It is a paid service, unless your [service agreement](/item-register/service/service-agreement.md) covers it. [Contact us](https://sbtinstruments.com/contact) to book it.
{% endhint %}
## Can I keep using my BactoBox®?
Yes. The light means your setup is approaching a failure mode, not that it has failed. Your BactoBox® still works as intended.
## What turns the light on
The light appears when any of these is true:
* A year has passed since the last preventive maintenance.
* You have run 2 000 programs, such as measurements, since the last preventive maintenance.
* The latest QC test shows that your setup is approaching a failure mode.
---
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