These instructions apply to the Lexus IS Mk3 (XE30) 2013-2020. For other models, please choose your vehicle here.
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Disconnecting the 12 V battery on your Lexus IS (2013–2020) — for a new battery, winter storage, or work near the airbags — is straightforward once you know where the battery is. On the IS 300h hybrid it’s in the boot, not under the bonnet; on the petrol IS it’s in the engine bay.
Find the 12 V Battery First
- IS 300h (hybrid): the 12 V battery is in the luggage compartment (boot), usually on the right side under a trim panel. The under-bonnet terminals are for jump-starting only. Never touch the orange high-voltage cabling.
- IS 200t / 300 (petrol): the battery is in the engine bay, conventional location.
Disconnecting Safely
- Switch off and, after turning the ignition off, wait 1 minute before disconnecting.
- Disconnect the negative (−) terminal first, then the positive.
- Working near airbags or seat-belt pretensioners? Wait 90 seconds after disconnecting before such work.
Reconnecting and Re-initialising
Reconnect positive first, then negative. The IS then relearns a few items:
- Start/stop system re-initialises after reconnection.
- Power windows — if one-touch is lost, pull-up-and-hold at the top to relearn.
- Re-enter the clock, audio presets and settings.
If Something Isn’t Right Afterwards
- Warning lights (e.g. VSC/stability) usually clear once the relearns complete after a short drive.
- A persistent light stores a code — look it up on autodtcs.com.
- Fit a like-for-like battery (the 300h uses a specific small AGM-type aux battery).
Frequently Asked Questions
Where is the battery on a Lexus IS 300h?
In the boot (luggage compartment), usually right side under the trim — the under-bonnet terminals are only for jump-starting.
And on the petrol IS?
In the engine bay, conventional location.
Which terminal first?
Negative (−) off first, reconnect it last.
What needs resetting afterwards?
The start/stop system re-initialises, windows may need a one-touch relearn, plus the clock and presets.
If a warning light stays on after reconnecting, look up the code on autodtcs.com.
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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