Most push-to-start cars still start with a dead fob battery. Use the fob's emergency blade to open the driver door, then hold the fob against the start button or a marked backup spot, often on the steering column or center console, and press start; your owner's manual shows the exact spot. Afterward, replace the coin cell, usually a CR2032, CR2025, CR1632 or CR1620.
- A dead fob battery rarely strands you: most push-to-start cars have a backup start method that reads the fob at close range.
- The emergency blade hidden in most smart keys opens the driver door, often through a keyhole under a cap on the handle.
- Buy the battery number printed on the old cell; common sizes are CR2032, CR2025, CR1632 and CR1620.
- Most fobs keep their programming through a battery change; if yours stops working afterward, check the orientation first, then ask about a resync.
- If the dash will not light at all, the car battery is the likely problem, not the fob, and the backup start method will not help.
Can you start a car with a dead key fob battery?
Usually, yes. Most push-to-start vehicles can still read the fob at very close range when its battery is dead, so holding it against the start button or a marked backup spot gets the engine running.
It works because of how most smart keys are built. The battery powers the buttons and the signal that lets the car sense the fob from a short distance. Most smart keys also carry a chip the car can read at very close range using the car's own power, much like a traditional transponder key. With a dead battery you lose the walk-up convenience, but the car can still read the chip when the fob is held right at the reader.
If you have a traditional key with a metal blade and remote buttons in the head, a dead battery usually only kills the buttons. The chip in the head does not run on the battery, so you can unlock the door with the blade and start the car as normal.
The short video below shows a related call: a Toyota Camry unlocked and its battery reinstalled on site.
Unlocking a Toyota Camry and reinstalling the battery in Ventura, CA
How to get into the car when the fob is dead
Use the emergency blade. Most smart keys hide a metal key inside the fob, released by a small button or slide, and it opens the driver door.
- 1Release the blade
Find the small button or slide on the fob, press or slide it, and pull the metal key out of the case.
- 2Find the keyhole
On many cars the driver door keyhole is hidden under a plastic cap on the handle. The owner's manual shows how the cap comes off; work gently so you do not scratch the paint.
- 3Unlock and open
Turn the key to unlock and open the door. On some vehicles the alarm sounds when the door is opened this way, and it typically stops once the car recognizes the fob and starts.
If the blade was never cut to your car, which happens with some fobs bought online, it will not turn the lock. If you are reading this before you need it, test your blade in the door now. We cut emergency blades in the van, and it is a much easier fix on a normal afternoon than in a parking lot at night.
How to start the car with a dead fob, step by step
Get in, put your foot on the brake or the clutch as you normally would, and hold the fob right against the start button or the marked spot while you press start. Your owner's manual names the exact spot for your car.
- 1Find the spot in the manual
Look in the index under starting the engine or under the smart key section. If the printed manual is missing, many manufacturers post owner's manuals online, and we can help by phone.
- 2Hold the fob in place
Press the fob flat against the button or the marked spot. On some cars the way the fob faces matters, so if nothing happens, turn it around and try again.
- 3Press start
Press the start button the way you normally would, with your foot on the brake or the clutch. The car reads the chip at close range and should start.
- 4Plan your next stop
Once it is running, the car will usually keep running even if it shows a key warning. Pick up a fresh battery on the way, because you will need the backup method for every start until the battery is replaced.
We walk customers through this by phone. If you are stuck and cannot find the spot, call or text us from the car with the year, make and model, and we will talk you through it before anyone has to drive out.
How to replace a key fob battery yourself
Most fob batteries take a few minutes to change with a coin or a small flat tool. Read the size printed on the old cell first; most fobs use a CR2032, CR2025, CR1632 or CR1620.
- 1Remove the emergency blade
On many smart keys the opening notch is hidden behind the blade, so take the blade out first.
- 2Open the case gently
Twist a coin or a small flat screwdriver in the notch along the seam. Work around the seam instead of forcing one spot, because the clips are plastic and a cracked case turns a battery swap into a repair.
- 3Note how the old battery sits
Take a photo or note which side faces up before you take it out. The new battery goes in exactly the same way.
- 4Install the new cell
Match the size exactly. Handle it by the edges, slide it under the contacts and press it flat into the holder.
- 5Close and test
Snap the case shut all the way around, put the blade back, and test lock, unlock and an engine start.
| Option | Ventura County | San Diego County | Time on-site |
|---|---|---|---|
| CR2032 / CR2025 Battery Swap | $25-$45 | $30-$50 | 5-10 min |
| CR1632 / CR1620 Battery Swap | $25-$45 | $30-$50 | 5-10 min |
| Battery + Reprogramming Combo | $65-$125 | $75-$150 | 10-25 min |
Flat-rate ranges from our current price list. The exact quote depends on year, make and model, and the price we quote is the price you pay. Full details: Key Fob Battery Service in Ventura County or in San Diego County.
We carry the common fob batteries in the van, so a battery swap, or a battery plus reprogramming, gets done on the spot.
When a fob needs a resync after a battery change
Most fobs keep their programming through a battery change. If yours stops responding afterward, check the battery orientation and the contacts first; if those are right, the fob may have lost sync and needs the car to relearn it.
On some vehicles, a battery change can knock the fob's rolling code out of step with the car. Some cars relearn the fob after a few presses up close or a short procedure from the owner's manual, while others need a professional programmer.
Losing sync does not mean the fob is broken. Do not buy a replacement until someone has tried a resync. We resync fobs at the car, and if the battery also needs changing, the battery and reprogramming combo in the table above covers both in one visit.
| Option | Ventura County | San Diego County | Time on-site |
|---|---|---|---|
| Fob Resync After Battery Swap | $75-$125 | $85-$150 | 10-20 min |
Flat-rate ranges from our current price list. The exact quote depends on year, make and model, and the price we quote is the price you pay. Full details: Key Fob Programming in Ventura County or in San Diego County.
For the other reasons a fob stops responding, our key fob not working guide works through the checks in order.
How to avoid getting stuck with a dead fob again
Replace the fob battery at the first warning sign, and keep a working spare. A weak battery usually gives some warning before it quits.
- Watch for shrinking range, buttons that need a second press, or a low fob battery message on the dash.
- Coin cells last roughly 2 to 4 years. If you cannot remember the last change, plan one.
- Change the batteries in both fobs at the same time so they age together.
- Find your backup start spot now, while the fob works, instead of hunting through the manual in a dark parking lot.
- Make sure the emergency blade is cut to your car and actually turns the driver door lock.
- Keep a second fob. A dead battery is a nuisance, while losing your only fob is a much bigger job. Our spare key guide explains the difference.
When to call a locksmith about a dead fob
Call when the backup start method does not work, the blade will not open the door, or a fresh battery does not bring the fob back. Those point past the battery, and we diagnose them at the car.
| Option | Ventura County | San Diego County | Time on-site |
|---|---|---|---|
| Smart Key Battery & Diagnostics | $75-$150 | $85-$175 | 15-25 min |
| Emergency Blade Cutting | $75-$125 | $85-$150 | 10-20 min |
| Smart Key System Reprogramming | $150-$300 | $175-$325 | 30-45 min |
Flat-rate ranges from our current price list. The exact quote depends on year, make and model, and the price we quote is the price you pay. Full details: Push-to-Start / Smart Key in Ventura County or in San Diego County.
When a fob needs replacing rather than a battery, we cut and program the new one at the car. The video below shows a fobik key made that way for a Dodge Ram.
Fobik key made for a Dodge Ram in Oak View, CA
We run 6:00 AM to 11:30 PM, 7 days a week, across Ventura County, Santa Barbara County, San Diego County and Malibu, and typical arrival is under 30 minutes in our primary service areas. Pricing is a flat rate quoted by phone or text before we drive out. From Thousand Oaks to Escondido, we come to the car.
See push-to-start smart key service in Ventura County or in San Diego, and key fob battery service in Ventura County or San Diego for battery jobs.
