These instructions apply to the Audi A4 Mk5 (B9/8W) 2015-Present. For other models, please choose your vehicle here.
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Taking the 12 V battery off an Audi A4 (B9/8W, 2015–present) is a straightforward under-bonnet task. Here’s the safe order plus what to re-teach once power is back.
Battery Location
The 12 V battery sits in the engine bay, towards the bulkhead under a cover (you may need to lift a plastic trim panel to reach it). The petrol (TFSI) and diesel (TDI) A4 has no high-voltage system to worry about.
Disconnecting
- Turn the ignition off, take the key clear and wait a minute.
- Undo the negative (−) terminal first and move the lead aside.
- To remove the battery, undo the positive (+) and the clamp.
Reconnecting
- Connect positive (+) first, then negative (−) last.
- Reset the clock; the MMI reloads itself.
- Re-teach the one-touch windows — see our A4 window guide.
- Stop/start may behave conservatively for a drive or two while the battery monitor relearns.
A matching battery doesn’t strictly need coding, but a different type/capacity should be registered to the battery-management system with an OBD tool.
Frequently Asked Questions
Negative or positive first on the A4?
Negative (−) off first and on last.
Does a new Audi A4 battery need coding?
A like-for-like battery generally doesn’t; a different type/capacity should be registered for correct charging.
Will I lose my MMI or radio?
No code is normally needed — just reset the clock; the MMI reloads.
Why won’t my windows auto-close now?
The power cut wiped their learned travel. A quick re-initialise fixes it.
Any warning light that stays lit? Look it up on autodtcs.com. To clear the service message, see our A4 B9 service reset.
Disclaimer: The information on this page is provided for general guidance only. Always follow your official service manual and safety precautions when working on your vehicle. We are not responsible for errors, omissions, or any damage resulting from the use of this information.
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