can the key in altima key fob start car

[CaliRose]

Yes, the physical key blade inside your Nissan Altima key fob can start the car, but only if the key fob's battery is dead. Under normal circumstances, you should never need to use it for starting. The key blade is primarily for unlocking the driver's door manually if the key fob fails.

The modern Nissan Altima uses a Push Button Ignition system that relies on a passive anti-theft system. When you enter the car with the key fob, the vehicle detects its unique signal and allows the engine to start when you press the brake pedal and the ignition button. The physical key blade itself does not contain this electronic chip.

If your key fob battery dies, the car won't recognize the fob. Here's the correct procedure:

1. Use the physical key blade to unlock the driver's door (the keyhole is often hidden under a cap on the door handle).
2. Once inside, place the entire key fob itself—not just the metal blade—directly against the ignition button. This is often called the "dead key fob" or "emergency start" position.
3. While the fob is pressed against the button, press the brake pedal and then press the ignition button. The car should now start, as it uses a low-frequency signal (NFC) to read the fob even without battery power.

Function	Key Fob (Battery Working)	Physical Key Blade (Inside Fob)
Unlock Doors	Remotely via button	Manually, via door lock cylinder
Start Engine	Yes, via Push Button Start	No, blade is mechanical only
Emergency Use	N/A	Used to unlock door when fob dead
Anti-Theft Role	Electronic signal (immobilizer)	Mechanical cut only

The key takeaway is that the metal blade and the electronic fob work as a team during an emergency. The blade gets you in the door, and the proximity of the dead fob itself allows you to start the car. Rely on the push-button system for daily use and keep a spare fob battery handy.

[LeMaximus]

From my experience, that little metal key is just for getting you in the car if the fob dies. You pop it out, unlock the door, but then you’ve got to hold the dead fob right up to the start button to get the engine going. The key itself can’t start it—the car needs to sense the fob’s chip, even if the battery's dead. It’s a backup plan, not the main event.

[Alfie]

Think of it like this: the physical key is your ticket into the stadium, but the key fob is the ticket to your actual seat. You need both. The metal key gets you inside the car when the electronics fail. But to start the engine, the car’s computer has to recognize the encrypted signal from the fob’s internal chip. The blade has no way to communicate with the computer, so it can't start the car on its own.

[AbigailDella]

I learned this the hard way when my key fob battery died at the grocery store. I used the little key to get in, but then I was just sitting there pushing the start button with no result. I finally called roadside assistance, and they told me to press the fob right against the button. It worked instantly. The mechanic later explained the car has an immobilizer system that the metal key can't bypass. So, the key is just for the door.

[McCassandra]

It's a common misconception. The answer is no, the key blade cannot start the car by itself. Its sole purpose is mechanical entry. The vehicle's security depends on an electronic handshake between the fob's transponder and the engine control unit. This immobilizer system prevents hot-wiring. So, while the blade is a crucial part of your emergency kit, its role is limited to unlocking. Starting the engine requires the electronic identity verification only the fob body provides.