Start the Car With a Dead Key Fob Battery

Last updated: June 12, 2026

A flat fob battery will not strand you in the Infiniti Q50 (V37, 2013–2023). This Nissan-group saloon uses the Infiniti Intelligent Key, and its push-button START/STOP switch has a backup antenna built in — so a dead coin cell still lets you start the car by holding the fob against the button. Below are the start procedure, how to unlock with the hidden blade, and how to fit a fresh battery.

Start the Q50 with a dead fob battery

The START/STOP button reads the Intelligent Key’s transponder through a short-range field, so a flat cell does not stop the V37 starting.

1. Sit in the driver’s seat with the doors closed and press the brake pedal fully.
2. Hold the fob so the Infiniti badge on the front of the key touches the START/STOP button.
3. A chime confirms the car has read the chip. Within about 10 seconds, press the button while keeping the brake down.
4. The engine starts. Keep it running until a fresh battery is fitted — a later restart may not be recognised.

Unlock the doors with the mechanical key

A dead fob disables the remote buttons and the keyless walk-up entry, so open the Q50 with the emergency blade.

1. Slide the release catch on the back of the Intelligent Key and pull the metal blade free.
2. Insert the blade into the driver’s door lock and turn to unlock.
3. Open the door. The alarm may sound briefly until the engine is started with the key recognised inside.

Immobiliser note

The Q50 immobiliser is paired to a passive transponder inside the Intelligent Key. Because the START/STOP button powers that chip directly when the fob touches it, an authorised key still works with a completely dead coin cell. A flat battery only disables remote locking and proximity detection — starting on this push-button car is unaffected.

Replace the key-fob battery

The Q50 Intelligent Key uses a single CR2032 3 V lithium coin cell. Confirm the type printed on the old battery before buying a replacement.

1. Slide the mechanical blade out first to release the case.
2. Prise the two halves apart at the seam with a coin or small flat-blade screwdriver.
3. Lift out the old cell and fit the new CR2032 the correct way up, close the case, reinsert the blade, and test the buttons.

Frequently Asked Questions

Why does my Q50 say “No Key Detected”? A flat fob battery is the most common cause. Touch the fob to the START/STOP button to start, then replace the CR2032.

Which side of the fob do I hold against the button? The face with the Infiniti badge. Hold it steady until the chime, then press the button within about 10 seconds.

What battery does the Q50 fob take? A CR2032 3 V lithium coin cell, widely available for a couple of pounds.

Will driving with a dead fob cause damage? No. Only remote locking and walk-up entry stop. The passive immobiliser transponder keeps working normally.

The Q50 started but a key warning stays on the dash — normal? Yes. The warning persists until you fit a fresh cell, then it clears on the next start.

If a key-detection problem appears together with a dashboard warning light or a stored fault code, our sister site autodtcs.com explains what each OBD-II trouble code means.