> ## Knowledge Base Index
> Fetch the complete knowledge base index at: https://teslemetry.crisp.help/sitemap.xml
> Use this file to discover available pages before exploring further.
> Pure-Markdown content can be obtained by appending a '.md' suffix to the content URLs listed in the sitemap (without the trailing slash).

# Legacy Vehicle Support and Limitations

This FAQ covers Teslemetry's support for older Tesla vehicles, including pre-2021 Model S and Model X, and explains the differences between streaming and polling data collection methods.

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## General Questions

### Can I use Teslemetry with my older Tesla vehicle?

Yes, Teslemetry supports older Tesla vehicles, though the features and data collection methods vary depending on your vehicle's hardware:

* **Pre-2021 Model S/X with MCU2**: Fully supported with Fleet Telemetry streaming (requires firmware 2025.20 or newer)
* **Pre-2021 Model S/X with MCU1**: Supported with polling-based data collection only

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## Streaming vs Polling

### What is the difference between streaming and polling?

**Streaming (Fleet Telemetry)**
* Your vehicle actively pushes data to Teslemetry in real-time
* Does not wake or keep your vehicle awake
* More cost-effective (no expensive API calls required)
* Available on modern vehicles (2021+) and legacy MCU2 vehicles with firmware 2025.20+

**Polling**
* Teslemetry's own service periodically requests data from your vehicle via Tesla's API - this runs server-side, no client or integration needs to manage it
* Teslemetry intelligently identifies when your vehicle is trying to sleep and will pause polling

### What is the polling interval for legacy vehicles?

Legacy vehicles (pre-2021 Model S/X with MCU1) have a polling interval of **90 seconds** while awake and active.

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## Vehicle Sleep

### Will polling prevent my legacy vehicle from sleeping?

Frequent data requests can prevent legacy vehicles from entering sleep mode. To address this, Teslemetry's server-side polling implements sleep protection:

1. When your vehicle has shown no activity for 15 minutes, Teslemetry pauses data polling to give it a chance to fall asleep
2. Lightweight state checks continue every 90 seconds - these do not keep the vehicle awake
3. Once the vehicle falls asleep, data polling stops entirely and resumes automatically when the vehicle comes back online or becomes active again

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## Subscriptions and Pricing

### Is polling included in my legacy vehicle subscription?

Yes. Legacy vehicles that cannot use Fleet Telemetry have polling included as part of their vehicle subscription at no additional cost.

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## Enabling Fleet Telemetry on Legacy MCU2 Vehicles

### My legacy Model S/X has MCU2. How do I enable streaming?

If you have a pre-2021 Model S or Model X with MCU2:

1. Ensure your vehicle has firmware 2025.20 or newer
2. In your vehicle, navigate to: **Settings > Safety > Allow Third-Party App Data Streaming**
3. Enable the data streaming option
4. Log in to the [Teslemetry Console](https://teslemetry.com/console) and select your vehicle
5. On the vehicle dashboard, click **Telemetry Configuration**
6. Select the fields you want to stream - changes save automatically and show a pending-delivery warning until the vehicle receives them

Unlike modern vehicles, legacy MCU2 vehicles do not require virtual key installation to use Fleet Telemetry.

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## Additional Resources

* [Vehicle Sleep Documentation](https://teslemetry.com/docs/topics/sleep)
* [Telemetry Configuration Guide](https://teslemetry.com/docs/getting-started/telemetry)
* [The Road Away From Vehicle Polling](https://teslemetry.com/blog/road-away-from-polling)