Disconnect and Reconnect the Battery

Reviewed by the Service Reset editor · Updated August 9, 2026 · How we verify
Quick referenceTools10 mm spannerTime~15 minMethodDisconnect negative terminal first

These instructions apply to the Lexus NX Mk1 (Z1) 2014-2021.
For other models, please choose your vehicle here.

Disconnecting the 12 V battery on your Lexus NX (2014–2021) — to fit a new one, store the car, or work near the airbags — is straightforward, but on the NX 300h hybrid the 12 V battery isn’t where most people look. Here’s where it is and the safe sequence.

Lexus NX Mk1 — the vehicle covered in this guide.
Lexus NX Mk1. Photo by Alexander Migl via Wikimedia Commons, licensed CC BY-SA 4.0.

Find the 12 V Battery First

On the NX 300h hybrid, the 12 V battery is in the luggage compartment (under the boot floor), not under the bonnet — there are only jump-start terminals under the bonnet. On the 200t / 300 petrol NX, the 12 V battery is in the engine bay. Either way, this 12 V battery is the one you service — never touch the orange high-voltage cables or the hybrid battery.

Disconnecting Safely

  1. Switch off and make sure all electrical consumers are off.
  2. Disconnect the negative (−) terminal first, then the positive.
  3. Working near airbags or pretensioners? Wait 90 seconds after disconnecting before starting.

Reconnecting and Re-initialising

Reconnect positive first, then negative. The NX then needs a few items re-initialised, which mostly happen by driving:

  • Steering angle sensor — drive straight and turn fully each way; the relearn completes on the move.
  • Parking-assist / camera calibration.
  • Re-enter the clock, audio presets and settings.

If Something Isn’t Right Afterwards

  • Warning lights after reconnection (e.g. steering/assist) 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 hybrid uses a specific AGM-type aux battery).

Frequently Asked Questions

Where is the 12 V battery on a Lexus NX 300h?

In the luggage compartment under the boot floor — the under-bonnet terminals are for jump-starting only.

Is it safe to disconnect the 12 V on a hybrid?

Yes — the 12 V is separate from the high-voltage system; just never touch the orange HV cabling.

Which terminal first?

Negative (−) off first, reconnect it last.

What needs resetting afterwards?

Steering-angle and parking-assist re-initialise (mostly by driving), plus the clock and presets.

If a warning light stays on after reconnecting, look up the code on autodtcs.com.

Independent guide — not affiliated with Lexus. Always follow your official service manual and safety precautions. Read our full disclaimer.

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