> For the complete documentation index, see [llms.txt](https://knowledge.illumina.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://knowledge.illumina.com/instrumentation/miseq/instrumentation-miseq-troubleshooting-list/000002353.md).

# Troubleshooting "Y home sensor never tripped" error on MiSeq

The MiSeq may give the error "Y stage encountered homing error when MiSeq was doing “Home All” function" or “Y home sensor never tripped" during MiSeq Control Software (MCS) initialization or during a run. This error will likely cause an ongoing run or initialization to fail.

**Troubleshooting steps**:

1. Perform a post-run wash if the run stops prematurely or after the run is completed.
2. Power cycle the MiSeq following the steps outlined in [How to Power Cycle the MiSeq](/instrumentation/miseq-ruo/instrumentation-miseq-ruo-reference_material-list/000001894.md).
3. Re-start the MCS and, if no issues with re-initialization, perform the **Y Stage test five times.** Instructions on how to perform system checks are outlined in [How to perform a System Check on the MiSeq.](/instrumentation/miseq/instrumentation-miseq-reference_material-list/000001777.md)
   * Make sure that a used flow cell is loaded on the instrument (eg, the same flow cell used for the wash).
   * Select Y Stage test.
     * For MCS v4.0 and above: From the Main Menu, select System Check.
     * For MCS v3.1 and below: From the Welcome Screen, select Manage Instrument, then select System Check.
   * Follow the on-screen prompts to start the test, and then repeat the test four more times (for a total of five times).
4. If all Y Stage tests pass, continue with normal sequencing.
5. If the system fails to initialize or any of the five replicates of the Y Stage test fail, contact [Illumina Technical Support](https://www.illumina.com/company/contact-us.html#/) for further assistance.

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| *For any feedback or questions regarding this article (Illumina Knowledge Article #2353), contact Illumina Technical Support* [*techsupport@illumina.com*](mailto:techsupport@illumina.com?subject=Question%2FFeedback%20Regarding%20Illumina%20Knowledge%20Article%20#000002353%20-%20Instrumentation%20\&body=Dear%20Illumina%20Technical%20Support,%0D%0A%0D%0A)*.* |


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