How to Start a Car With a Dead Key Fob, Brand by Brand

On July 7, 2024, the official reading at Harry Reid International Airport hit 120 degrees, the hottest day Las Vegas has ever logged, KOMO News reported from National Weather Service data. Picture a driver walking out of a Henderson grocery store that week. The unlock button does nothing. Inside, the start button flashes and the dash says no key was found. We want that driver to know one thing before panic sets in. The car will very likely start in the next two minutes.

A dead key fob almost never strands you. Open the driver door with the metal blade hidden in the fob, then hold the fob right against the start button, or set it in the backup pocket or slot your car maker built in. Keep the brake pressed and push start. If nothing lights up at all, the problem is more likely the car battery than the fob.

• Toyota, Honda, Nissan and Hyundai manuals all say to touch the fob to the start button
• Ford and Chevrolet use a backup pocket or slot, and the spot changes by model
• Nissan gives you 10 seconds after the chime, and Honda keeps its button flashing for about 30 seconds
• Skip the brake and many cars only switch to accessory mode
• Toyota rates the battery in its electronic key at 1 to 2 years
• A cracked, wet or lost fob needs a new key programmed, not a new battery

Check Whether It Is the Fob or the Car Battery

Spend 30 seconds on this first, because the fix is different. A dead fob leaves the car itself awake. The dome light still comes on when a door opens, the dash still lights up, and the car tells you it cannot find the key. Chevrolet says its cars show a Driver Information Center message that no key fob was detected and ask you to use the key pocket, as its Keyless Open and Keyless Start page explains.

A dead car battery looks darker. Nothing lights, nothing clicks, and the fob buttons seem to fail too. Toyota UK warns that a fully drained 12 volt battery can stop smart entry and other electrical parts from working as expected. In that case the fob tricks below will not help. You need a jump start or a charge.

One more check. If a second fob lives in a drawer at home, try it before anything else. If the spare works, you know the car is fine and the old fob needs a battery.

Open the Door With the Hidden Blade

The smart fobs from Ford, Hyundai, Toyota and Chevrolet all hide a short metal key. Ford says to slide the release on the back of the fob and pull the blade out. The keyhole sits on the bottom or side of the driver door handle, often under a cap.

On many Hyundai models the keyhole hides behind a plastic cover on the handle. The Hyundai owner's manual says to release that cover from the underside of the handle, then use the key in the cylinder. Press gently on the plastic. A screwdriver jammed in at an angle is how these caps crack.

Expect noise. The Toyota owner's manual says the alarm may go off when a door is opened with the metal key while the alarm is set. Get in, shut the door and start the car, and it should settle. Our post on why a car will not unlock with the key or remote covers stuck cylinders and other entry problems.

Where to Hold the Fob, Brand by Brand

Every maker on this list gives you one spot where the car can still read a weak fob, either right on the start button or in a backup pocket or slot. The table pulls the steps from each maker's own manual or support page.

Not on the list? Look in the index of your owner's manual under the key, the smart key, or starting the engine. Many cars also keep a printed copy in the glove box. Ford sends owners to the section called Starting and Stopping the Engine, and Chevrolet says its pocket location changes by model, so the manual is the final word.

Hold the fob still and flat. Waving it around the button gives the reader less time to catch it. On a Honda, the side with the H logo goes against the button. On other brands, try the logo side first, then flip it.

When the Backup Start Still Fails

Start with the brake. The Nissan manual says that if you push the switch without the brake, the ignition turns on instead of the engine. Honda says the car drops into accessory mode. The Toyota manual says each press without the brake just changes the power mode. Press the brake hard, then try again from the top.

Timing is the next trap. Nissan gives you 10 seconds after the chime. Honda keeps the button flashing for about 30 seconds, then gives you 10 seconds after the beep. Miss the window and you start over.

Something nearby can also get in the way. Ford Canada says a fob with no charge, or one whose signal is jammed, will not start the car unless it sits in the backup slot. Move phones, chargers and other key fobs away from the console while you try.

If none of that works, the fob may be the real problem, not its battery. A fob that went through the wash, got crushed, or cracked open can lose the part the car reads. Toyota tells owners to see a dealer if the system still will not start. A licensed locksmith can often program a new key on site instead, with no tow. In Nevada, a locksmith needs a permit from the county sheriff under NRS chapter 655, so ask to see it.

Replace the Coin Cell Before It Strands You Again

Getting the car started buys you time. It does not fix the fob. The Toyota manual calls the backup start a temporary measure and says to replace the key battery right away. It rates the battery at 1 to 2 years and warns that the range shrinks as it fades.

Watch for the warning. Toyota sounds an alarm in the cabin and shows a message when the key battery runs low. Shorter unlock range is the other early sign. Change the cell the week you notice either one.

Find the battery size before you shop. That Toyota manual calls for a CR2450, and so does the Hyundai manual for its smart key. Other fobs use other sizes, so open the fob or check the manual. The number is printed on the cell itself.

Heat is part of the story here. The National Weather Service says a closed car can warm about 20 degrees in 10 minutes and about 50 degrees in an hour, even on a 70 degree day. In a valley that has hit 120, the inside of a parked car is a rough place for any small battery. Keep spare cells at home in a cool drawer, not in the glove box.

Store them safely, too. Toyota warns that a swallowed coin battery can cause severe chemical burns in as little as 2 hours. Keep new and used cells where children cannot reach them.

Dead Fob in Henderson or Las Vegas?

Tried every step and still stuck? Call (702) 979-7566. We open locked cars and make replacement car keys and fobs on site across Henderson and the Las Vegas valley, day or night, and we give you the price before we start. Locked out as well? Our car lockout service handles that too.

Official Pages

More to Read

• Why a car will not unlock with the key or remote
• What to do after losing your only car key
• Keys locked in the car with no spare