> For the complete documentation index, see [llms.txt](https://docs.twtg.io/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.twtg.io/docs/how-to/vibration-sensor-vb/how-to-debug-a-not-connected-sensor.md).

# How to debug a not connected sensor

The Built-In Self Test (BIST) will fail indicating that no sensor is connected with the BIST = 0x4F (79). This could be due to:

### Sensor connection

There's no sensor connected to the transmitter or the sensor is not properly connected. Ensure that the probe is in place and that the O-ring is tightly adjusted.

### Malfunctioning sensor

If the sensor is connected properly, another cause for the reported issue could be that the sensor being used is malfunctioning. To verify this follow the next steps:

1. Ensure there are no visible damages in the probe or cable of the sensor. 
2. If available, try a different probe that is working properly. To do this follow the steps on [how to replace the sensor or probe](/docs/how-to/vibration-sensor-vb/how-to-replace-the-sensor-or-probe.md). If the NEON Vibration Sensor works with the new probe, then it's extremely likely that the old probe is damaged/malfunctioning. Contact TWTG through the [service desk](https://www.twtg.io/servicedesk) to arrange a replacement if the device is under warranty.

### No connection between the transmitter's PCB and the sensor's PCB

In very unlikely scenarios the cable between the transmitter's PCB and the sensor's PCB can be disconnected. If this is the case, contact TWTG through the [service desk](https://www.twtg.io/servicedesk) to arrange the device's repair.


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation by asking a question.

Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters:

```
GET https://docs.twtg.io/docs/how-to/vibration-sensor-vb/how-to-debug-a-not-connected-sensor.md?ask=<question>&goal=<user_goal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.