Start the Car With a Dead Key Fob Battery

Last updated: June 12, 2026

The Suzuki SX4 S-Cross (Mk1/JY, 2013–2021) came with Suzuki’s keyless smart entry and a START/STOP button on SZ5 and Keyless trims, and with a remote flip key in an ignition barrel on lower SZ3 and SZ4 trims. When the smart fob’s coin cell goes flat the remote-lock buttons die, but the immobiliser still reads the key — on push-button cars by holding the fob against the start switch, on flip-key cars via the blade in the barrel.

Start a keyless S-Cross Mk1 with a dead fob

If your S-Cross has the START/STOP button:

1. Unlock and enter the car with the emergency blade first (next section), sit in the driver’s seat and close the door.
2. Press and hold the brake pedal with the selector in N (manual) or P (auto).
3. Hold the flat back of the smart fob directly against the START/STOP button — the button carries a short-range coil that reads the fob at close contact.
4. With the fob still pressed to the button, push the START/STOP button. The engine starts.
5. If it does not catch first time, hold the fob flush against the button and try again — a weak cell needs the fob touching the switch.

Turn-key S-Cross Mk1 — the blade starts it

On an SZ3 or SZ4 with an ignition barrel, a flat fob disables only the remote buttons. Pull the blade from the flip key, unlock the driver’s door, slot the key into the barrel and start the car the usual way. The transponder in the key head is powered by the barrel, so a dead coin cell does not stop it starting.

Unlock the S-Cross Mk1 with the emergency key blade

1. Slide the release catch on the back of the smart fob and pull the metal blade free of the body.
2. Insert the blade into the lock barrel in the driver’s door handle and turn to unlock.
3. The alarm may sound until the engine is started; running the car clears it.

Immobiliser note

The S-Cross immobiliser reads a passive RFID transponder, not the fob battery. On a keyless car the back-up reader is inside the START/STOP button; on a turn-key car the ring around the barrel does the same job. The car powers the reader, so the engine authorises even with a fully dead fob. A key warning still lit after starting points to a genuine fault rather than a flat cell.

Replace the fob battery

The S-Cross Mk1 smart fob uses one CR2032 3V lithium coin cell; some early flip keys take a smaller CR1620, so check the old cell before buying. Slide out the emergency blade, split the case at the seam left behind, swap the cell + side up and click it shut. Remote functions return immediately.

Frequently Asked Questions

Does my S-Cross Mk1 have keyless start?

SZ5 and Keyless trims do, with a START/STOP button. SZ3 and SZ4 cars use a flip key in an ignition barrel and only need the blade.

Where do I hold the fob to start a keyless S-Cross?

Directly against the START/STOP button. This model has no key slot or column reader — the back-up coil is in the button itself.

Which battery does the S-Cross Mk1 fob take?

Most smart fobs take a CR2032; some early SX4 S-Cross flip keys use a CR1620. Match the marking on the old cell to be sure.

The remote stopped working but the car still starts — is that normal?

On a turn-key S-Cross, yes. A flat cell kills only the remote buttons while the transponder still starts the engine. Replace the cell at your convenience.

Why did the alarm sound when I used the blade?

Mechanical entry registers as a possible break-in until the transponder is read. Starting the engine cancels the alarm.

If a dashboard warning light stayed on after the no-start, look it up on autodtcs.com to confirm it was just the fob and not an immobiliser code.