How to Start a Car With a Key Fob (Dead Battery Backup Included)

To start a push-button car with a key fob, keep the fob inside the car, press and hold the brake pedal, then press the Start/Stop button once. Without the brake, the button only cycles through accessory and ignition-on modes. If the fob battery is weak, many makers build in a backup: you touch the fob to the button or place it in a marked spot, then press the button with your foot on the brake. This guide covers the steps, the backup spot by maker, and remote start.

Understanding Your Key Fob

A push-button car does not need the fob to be turned or inserted. It listens for it. Subaru’s manual says its system works on weak radio waves, so a depleted battery, strong radio sources or metal touching the fob can stop detection. Honda says you can start the engine when the keyless remote is inside the vehicle, and that it may also start if the remote is close to a door or window outside.

The fob also has to be the right one. Honda’s manual says its immobilizer system protects the vehicle from theft and disables the fuel system if an improperly coded device is used, so an unregistered fob will not start the car. See also what a key fob is.

How to Start a Car with a Key Fob: Step-by-Step

These steps follow the owner’s manuals of Hyundai, Honda, Chevrolet and Subaru. Wording differs by make, so your own manual has the final word. For a shorter walkthrough, see our guide to starting a push-start car covers the same basics.

Step 1: Unlock Your Car

Press the unlock button on the fob, or use the door-handle sensor if your car has one. Chevrolet’s Silverado manual lists the remote transmitter, keyless access and the key in the door as the ways to unlock from outside.

Step 2: Get Inside and Ensure Fob Presence

Keep the fob with you in the cabin. Hyundai says the car may not start if the smart key is not near you, for example in the cargo area. Honda warns against leaving the remote on the dashboard or in the glove box, and says that if the remote leaves the car after the engine starts you can no longer change modes or restart.

Step 3: Prepare for Starting

Shift to P (Park). Hyundai and Chevrolet allow P or N, and Hyundai recommends P for safety and lists applying the parking brake. Subaru says manual cars should be in neutral with the clutch pressed. Hyundai also says to wear proper shoes and not to start with the accelerator pressed.

Step 4: Press the Brake Pedal

Press and hold the brake firmly. This decides whether you get a start or just a mode change. The table follows Hyundai’s manual.

Button position	How you get there	What it does
OFF	Press the button with the car in P and the engine running	Turns the engine off
ACC	Press the button from OFF without the brake	Some accessories work; Hyundai says power turns off automatically after one hour
ON	Press again from ACC without the brake	Warning lights come on; do not leave it here with the engine off or the battery can run down
START	Press with the brake pedal held, in P or N	Starts the engine

On manual cars the clutch does the same job: Subaru says the engine cannot start unless the clutch pedal is fully depressed.

Step 5: Press the Start/Stop Button

Press the button once and let go as the engine cranks. Honda says not to hold it, and to wait at least 30 seconds before trying again. Hyundai says not to press it for more than 10 seconds, except when a warning says the brake switch fuse is blown. Chevrolet says to wait at least 15 seconds between tries so the cranking motor can cool.

If Your Car Has a Key Instead of a Button

Some fobs hold a key that turns in an ignition. Chevrolet’s Silverado manual separates the two: on Key Access vehicles you turn the key to Start and release it, while on Keyless Access vehicles the transmitter must be in the vehicle and you press Start/Stop with the brake applied.

What to Do if Your Car Doesn’t Start

Match what you see to the likely cause. Each row comes from the manual named.

What you notice	Likely cause	What the manual says
Button lights up but the engine does not crank	Brake not pressed firmly	Hyundai and Honda: without the pedal the mode changes instead of starting
“Key not in vehicle” warning	Fob not in the cabin or not near the driver	Hyundai: appears when a door is open and no key is detected; keep the key inside
Beeper, flashing button and a message to touch the button with the remote	Weak fob battery on a Honda	Honda: follow its backup steps (see the table below)
A fault message about the brake switch fuse	Blown brake switch fuse	Hyundai: with the button in ACC, press and hold it for 10 seconds, then replace the fuse soon

If the dashboard stays dark, the problem may be the car’s battery. See starting a car with a dead battery.

Troubleshooting Common Key Fob Issues

Dead Fob Battery

Subaru’s manual gives a standard fob battery life of 1 to 2 years, says the key drains even when unused, and lists symptoms: the system not responding, a smaller detection area and the key’s LED not lighting. It names a CR2032 for keyless access keys, as does Chevrolet for its transmitter. Other fobs use other cells, so check yours.

Chevrolet warns that a swallowed coin battery can cause internal burns, severe injury or death, so seek medical attention immediately if one is swallowed, and use the correct battery type. See our guides to changing a car key battery and smart key lithium batteries.

Key Fob Not Recognized

If the battery is fine, look for interference. Subaru lists strong radio sources such as TV towers, gas stations and airports, metal contact from coins, foil-lined cards and metallic wallets, a phone or another vehicle’s key carried with the fob, and metallic window tint. Mazda adds that other immobilizer keys near the fob can stop it being read during a backup start. See the key not detected message.

The Importance of the Physical Key and Backup Methods

A dead fob causes two problems, getting in and starting, and the backups differ. The metal key handles the doors. The engine backup, in the manuals read for this guide, uses the fob itself.

Locating and Using the Physical Key

Subaru’s manual says to push the release knob and take the mechanical key out of the access key, and to carry it with the fob, since it is needed if the battery is depleted. It adds that unlocking with it while the alarm is set may trigger the alarm. Chevrolet says to press the transmitter’s button to release its key and never pull the key out without pressing it.

The Hidden Key Slot for Push-to-Start Vehicles

A common belief is that the hidden key goes into a hidden ignition slot. In the manuals read here, the engine backup works differently: you touch the fob to the Start/Stop button, hold it over the button, or put it in a marked slot or pocket, then press the button with the brake held. The exact spot varies by make, model and often trim, so treat this table as examples and check your own manual.

Manual read	Backup start steps (brake pedal held for the final press)
Honda CR-V (2023)	Press Start/Stop. A beeper sounds and the button flashes for about 30 seconds. Touch the center of the button with the H logo on the remote, buttons facing you. When it stays on for about 10 seconds, press the brake and the button.
Hyundai (2025 manual, model code NX4)	Press the Start/Stop button with the smart key itself, in the position shown in the manual picture, with the car in P and the brake pressed as for a normal start.
Hyundai (2026 manual, model code LX3)	Place the smart key in the smart key slot for emergency starting, then press the Start/Stop button.
Ford (owner’s manual)	Place the remote in the backup slot, buttons facing the rear: under the mat in the console cup holder, or under the storage compartment lid, depending on the vehicle. Press the brake, then the push button ignition switch.
Chevrolet Silverado (2020)	If the display says no remote is detected, place the transmitter in the transmitter pocket (position depends on bucket seats). In P or N, press the brake and Start/Stop.
Subaru BRZ (US edition)	In P with the brake pressed, touch the area behind the lock and unlock buttons of the access key to the push-button switch. A buzzer sounds. Press the brake firmly, check the green indicator is on, and press the switch.
Mazda CX-30	Park, hold the brake, and wait for the green indicator on the button to flash. Align the emblem on the transmitter with the center of the button until the light stays on, then press the button.

Ford’s support page says the slot can be in the console storage compartment, the cup holder or elsewhere depending on year and model: see Ford’s support page. Honda’s low-battery steps are on Honda’s CR-V manual page.

Treat any backup start as temporary: Subaru calls it a temporary measure, and Chevrolet says to replace the battery as soon as possible. More in our page on what to do about a dead key fob.

How to Remote Start Your Car From Inside the House With the Key Fob

Remote start exists only on equipped cars, and each maker sets its own button sequence, range and run time. See also keyless entry vs remote start.

Manual read	Starting it	Run time and limits
Hyundai (2025 manual, model code NX4)	Press lock within 32 ft (10 m), then hold the remote start button over 2 seconds within 4 seconds. Press it once to turn off.	Hood or liftgate open: no start. Must be in P. Turns off if you do not get in within 10 minutes.
Honda CR-V (2023)	A two-step press on the remote; lights flash six times if the engine starts. Press and hold the button one second to stop.	Shuts off after 10 minutes unless extended. No start if the hood is open, a door is unlocked or the car is not in P.
Chevrolet Silverado (2020)	Press and release one button, then press and hold remote start until the turn signals flash, at least four seconds.	Runs 15 minutes, one extension (30 total). No start if the transmitter is inside or the hood is open.

Honda warns that carbon monoxide is toxic, builds up rapidly in closed or partly enclosed areas and can cause unconsciousness or death, so never use remote start with the car in a garage or other poorly ventilated space. Honda says remote start may violate local laws, and Chevrolet says some communities restrict remote starters, so check your local rules.

Honda says buildings and obstacles reduce range. See extending remote starter range and starting a car in cold weather.

When to Call a Professional

• The backup steps in your manual do not work: Subaru says to contact a dealer if the switch still cannot be operated.
• An amber indicator keeps flashing at the button: Mazda says the engine may still start but to have the vehicle checked soon.
• A brake switch fuse warning appears: Hyundai says to replace the fuse soon.
• You have lost the fob or it is physically damaged: contact a dealer or locksmith, since a replacement fob has to be registered to the car.

For everyday fob safety, see preventing keyless car theft.

Frequently Asked Questions About Starting a Car With a Key Fob

Why does my car turn on but not start when I press the Start/Stop button?

Almost always because the brake pedal was not pressed. Hyundai’s manual says that without the brake the engine does not start and the button cycles through OFF, ACC and ON. Press the pedal firmly first, then the button.

Can I start my car if the key fob battery is completely dead?

Often yes, using the maker’s backup: touching or placing the fob in a marked spot, then pressing the button with your foot on the brake. The spot differs by make and model, so check your manual and replace the battery soon afterward.

Can the hidden key in a car fob be used to start a push-button car?

In the manuals read for this guide, the metal key is for the doors, and the engine backup uses the fob itself: touched to the button, held over it or placed in a slot. Your manual shows what applies to your car.

How do I start my car with the key fob from inside the house?

Only if the car has factory remote start, using a short button sequence on the fob within range. Never run a remote-started car in a garage or other poorly ventilated space, because carbon monoxide can build up quickly.

Final Thoughts on Starting a Car With a Key Fob

The routine is short: fob inside, shift to P, brake down, press the button once. When it fails, check the brake, the fob’s position, the fob battery and interference, then your own manual’s backup page.

What this guide does not cover: programming new fobs, repair or replacement prices, makers other than those named, and any way to start a car without a recognized key. For a lost fob, contact a dealer or locksmith.