Start the Car With a Dead Key Fob Battery

Last updated: June 12, 2026

The Suzuki Swift (Mk3/FZ-NZ, 2010–2017) was sold with two key types. SZ4 and Keyless-fitted trims use a smart fob and a START/STOP button; lower SZ2 and SZ3 trims use a remote flip key turned in an ignition barrel. When the fob’s coin cell dies the lock buttons stop responding, but the immobiliser still reads the key — on push-button cars by holding the fob against the start switch, on flip-key cars simply via the blade in the barrel.

Start a keyless Swift Mk3 with a dead fob

If your Swift has the START/STOP button:

1. Unlock and enter the car with the emergency blade first (next section), then sit in the driver’s seat and close the door.
2. Press and hold the brake pedal firmly with the car in neutral or park.
3. Hold the flat face of the smart fob directly against the START/STOP button — the button has a back-up coil that reads the fob at point-blank range.
4. Keep the fob pressed in place and push the START/STOP button at the same time. The engine cranks and starts.
5. If nothing happens on the first try, reposition the fob flush against the button and repeat — a nearly-flat cell needs the fob right on the switch.

Turn-key Swift Mk3 — the blade starts it

On an SZ2 or SZ3 with a conventional ignition barrel, a flat fob disables only the remote-lock buttons. Pull the blade from the flip key, unlock the driver’s door, then put the key in the barrel and start the car as normal. The transponder in the key head is energised by the barrel coil, so a dead battery does not stop it starting.

Unlock the Swift Mk3 with the emergency key blade

1. On the smart fob, slide the small release catch on the back and pull the metal blade free of the body.
2. At the driver’s door, insert the blade into the lock barrel in the handle and turn to unlock. Some trims hide the barrel behind a cap — lever it off with the blade tip first.
3. The alarm may chirp until the engine is started; starting the car clears it.

Immobiliser note

The Swift’s immobiliser checks a passive RFID transponder, not the fob battery. On a keyless car the START/STOP button houses the back-up reader; on a turn-key car the ring around the barrel does the same job. Either way the chip is powered by the car, so the engine authorises even when the fob is completely dead. If a key or immobiliser warning stays on after starting, it points to a genuine fault rather than just a flat cell.

Replace the fob battery

The Swift Mk3 fob uses one CR2032 3V lithium coin cell. Slide out the emergency blade, then split the fob at the seam where the blade sat — a coin or small flat screwdriver in the slot pops the halves apart. Lift the old cell out, drop the new one in with the + side facing the same way, and click the case shut. Remote locking works again immediately.

Frequently Asked Questions

Does my Swift Mk3 have keyless start?

Only SZ4 and Keyless-equipped trims do — those have a START/STOP button. SZ2 and SZ3 cars use a flip key in an ignition barrel and just need the blade.

Where do I hold the fob to start a keyless Swift?

Directly against the START/STOP button itself. There is no separate slot or column reader on this model — the button has the back-up coil built in.

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

On a turn-key Swift, yes. A flat cell kills only the remote-lock buttons; the transponder still starts the car. Replace the CR2032 when convenient.

Which battery does the Swift Mk3 fob take?

A single CR2032 coin cell, sold in any supermarket. Avoid touching the flat faces of the new cell with bare fingers, as skin oils can shorten its life.

Why did the alarm sound when I used the blade?

Mechanical entry looks like a forced break-in until the transponder is read. Pressing start and getting the engine running 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.