These instructions apply to the Hyundai i30 Mk2 (GD) 2012-2017.
For other models, please choose your vehicle here.
Disconnecting the 12 V battery on a Hyundai i30 Mk2 (GD, 2012–2017) is a routine job, but the car loses several settings while the power is off — the clock, radio presets, climate and trip-computer settings, and the one-touch windows — so it pays to do it in the right order and run the quick re-initialisations afterwards. This guide covers the safe sequence and the resets the i30 needs.
Where the Battery Is
The battery is in the engine compartment under a plastic cover. Lift the cover to reach the clamps. Cars with ISG (Idle Stop & Go) start/stop use an uprated AGM/EFB battery — replace like-for-like, because a standard battery will not cope with the stop/start cycling.
Before You Disconnect
- Check your audio system security code — some i30 head units lock after a power loss and ask for it.
- Note your radio presets and user preferences, which are wiped when the power goes.
- Make sure the ignition key is OFF and all electrical consumers are switched off before touching the terminals.
- If you want to keep settings alive, plug in a memory-saver. The steps below assume you are not.
- If working near airbags or seat-belt pretensioners, disconnect the battery and wait at least 3 minutes before handling those parts.
Disconnecting — Correct Order
- Turn the ignition off and remove the key.
- Open the bonnet and lift off the battery cover.
- Slacken the negative (−, earth) terminal first and lift the lead clear, tucking it aside.
- Only undo the positive (+) terminal if you are removing the battery completely.
- If removing the battery, undo the base clamp and lift it out upright.
Reconnecting — Correct Order
- Refit the battery and secure the hold-down clamp.
- Connect the positive (+) lead first, then the negative (−) earth lead last. Tighten both firmly.
- Do not start the engine immediately. Turn the ignition on for a few seconds first.
What to Reset Afterwards
- Enter the radio code if asked, and reset the date and time.
- Re-enter your radio presets and user preferences.
- Re-initialise the climate control — the electronic climate unit may need a moment to recalibrate; running it through its range helps.
- Reset the trip-computer settings (units, average figures) as preferred.
- Re-initialise the electric windows — see the quick steps below or the dedicated guide.
- Re-initialise the electric sunroof if fitted.
Quick Window Re-initialisation
- Turn the ignition on.
- Pull and hold the window close switch until the window is fully shut, then wait 1 second before releasing.
- Repeat for the passenger window (and rears).
Full detail is in our i30 Mk2 electric window reinitialisation guide.
When a Warning Persists
One or two lights right after reconnecting is normal and should clear on a short drive. If the airbag, ABS or engine light remains, a fault code was logged during the power interruption. Reading it needs an OBD scanner — you can look up what an i30 code means on our sister site autodtcs.com.
Tools You Need
- 10 mm spanner/socket for the terminal clamps and hold-down.
- Optional memory-saver to preserve presets and settings.
- Your radio keycode, if the head unit is code-protected.
Frequently Asked Questions
Why doesn’t my start/stop work after reconnecting the battery?
Hyundai’s ISG needs the battery sensor to relearn the state of charge before it allows auto-stop. Drive normally for a while and it should return; a new battery may need registering on ISG cars.
How long should I leave it disconnected to reset the electronics?
About 15 minutes with the doors shut lets the modules power down fully, clearing most transient glitches.
Why won’t my windows auto-close after reconnecting?
That is expected — the one-touch function disables itself after a power loss. Re-initialise each window and it returns.
Do I need to register a new battery on an i30?
On ISG/start-stop cars, yes — register a new AGM/EFB battery with a Hyundai-capable tool so the charging system manages it correctly.
To clear the service reminder after maintenance, see our Hyundai i30 Mk2 service indicator reset guide.
Independent guide — not affiliated with Hyundai. Always follow your official service manual and safety precautions. Read our full disclaimer.