These instructions apply to the Hyundai i30 Mk3 (PD) 2017-Present. For other models, please choose your vehicle here.
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The Hyundai i30 (Mk3/PD, 2017–Present), including the Fastback and N variants, was widely sold with keyless entry and a START/STOP button, though base trims keep a turn-key barrel. When the Smart Key’s CR2032 cell dies the remote buttons and proximity detection stop, but the i30 will still start if you press the fob directly against the start button — and turn-key cars are unaffected once you use the emergency blade.
Start a Smart Key i30 with a dead fob
For an i30 with keyless entry and a START/STOP button:
- Get inside using the emergency blade first (next section) and sit in the driver’s seat.
- Press and hold the brake pedal firmly.
- Hold the Smart Key so the back of the fob is flat against the START/STOP button.
- Push the START/STOP button with the fob still pressed against it.
- The reader behind the button energises the transponder and the engine starts.
Turn-key i30 — the blade still starts it
Base i30 trims use a flip key and an ignition barrel. A flat coin cell only disables the remote-lock buttons; unlock the driver’s door with the blade, insert it in the barrel and start the engine as normal. The barrel reads the key’s transponder directly, so the dead cell is irrelevant to starting.
Unlock the i30 with the emergency key blade
- Press the latch on the back of the Smart Key and pull out the metal emergency blade.
- Insert the blade into the lock slot on the driver’s door handle and turn to unlock.
- The alarm may chirp until the key is recognised — starting the engine silences it.
Why a flat fob still starts the i30
The coin cell only powers the remote buttons and the proximity broadcast for hands-free use. The chip that authorises the engine is a passive RFID transponder with no internal battery — the car wakes it through the coil behind the START/STOP button or the ignition barrel. Because that chip never relies on the cell, the immobiliser can still verify the key when the fob is completely dead.
Replace the fob battery
The i30 Mk3 Smart Key uses one CR2032 3V lithium coin cell. Slide out the emergency blade, then twist the case open at the seam with the blade or a coin. Replace the cell with the + side facing the same way and press the case shut. Remote locking and keyless start return immediately. Expect two to three years from a good-quality cell.
Frequently Asked Questions
Does my i30 have keyless start?
Most SE Nav and higher trims, plus the N, came with the Smart Key and a START/STOP button. Base cars use a barrel and only need the blade.
Where do I hold the fob to start the engine?
Press the back of the Smart Key flat against the START/STOP button, hold the brake, then push the button with the fob in place.
My i30 N still starts but the remote is dead — why?
A flat coin cell only kills remote locking and proximity. The transponder still works, so the engine starts. Fit a new CR2032 to restore the remote functions.
Why did the alarm sound when I used the blade?
Manual entry reads as a break-in until the transponder is verified. Starting the engine cancels the alarm.
Which battery does the i30 Smart Key take?
A single CR2032 3V lithium coin cell, available almost anywhere.
If a warning light remained on after the no-start, look it up on autodtcs.com to confirm it was just the fob and not a stored immobiliser fault.
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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