SoCal 24/7 Locksmith team
Older cars used a plain metal key: cut it to match the lock and you were done. Many newer cars add electronics, and the car won't start unless it recognizes that key.
Here's how to tell what you carry, how each type works, and what a car key replacement looks like for each one.
The quick comparison
| Key type | How you start the car | What a replacement needs |
|---|---|---|
| Mechanical key | Turn the key in the ignition | Cutting only |
| Transponder key | Turn the key; a chip in the head is checked by the car | Cutting plus programming to the car |
| Remote head key / switchblade | Turn the key; buttons lock and unlock | Cutting, chip programming and remote pairing |
| Smart key (proximity fob) | Push a start button with the fob nearby | Programming the fob; often an emergency blade cut too |
Names vary by manufacturer. Ford, for example, uses "Intelligent Access Key" for its push-button fob and "Integrated Keyhead Transmitter" for a key with remote buttons built into the head.
Transponder keys
A transponder key looks like an ordinary key with a thick plastic head. Inside the head is a chip. When you turn the ignition, the car reads the chip, and if it doesn't recognize the code, the engine won't run.
Ford describes its version, called SecuriLock or PATS, as a system that helps prevent anyone from starting the engine without a coded key programmed for that vehicle. Ford also notes that using the wrong key could keep the engine from starting.
Why a hardware-store copy won't start the car
A copy cut from the blade alone can open the door, but without a programmed chip it won't start the engine. That's the whole point of the system, and it's why transponder keys need programming equipment, not just a key machine.
Remote head keys and switchblades
These combine a transponder key with lock and unlock buttons. Some fold the blade into the head like a pocketknife. Replacing one means three things: cutting the blade, programming the chip, and pairing the remote buttons.
If only the buttons stopped working but the car still starts, the problem may be the battery or the remote side alone. That's worth checking before you replace the whole key.
Smart keys and proximity fobs
A smart key stays in your pocket or bag. The car detects it when you approach and lets you start the engine with a button.
- Where they came from: NHTSA says keyless ignition systems first appeared in luxury vehicles in the early 2000s and are now found in mainstream models.
- How the car checks them: NHTSA describes the car verifying the fob electronically when the driver presses the start button or turns a rotary switch.
- Dead fob battery: Ford's support pages describe a backup slot for starting the car when an Intelligent Access Key has no charge. Its location varies by model, so check the Starting and Stopping section of your owner's manual.
NHTSA lists three keyless-ignition risks: rollaway when the engine is shut off without selecting park, carbon monoxide when a car is left running in an enclosed space, and drivers who don't know how to shut off the engine in an emergency. Read your owner's manual on this before you need it.
How to tell which key you have
- Push-button start? You have a smart key or proximity fob.
- Turn-to-start key with buttons on the head? A remote head key or switchblade.
- Turn-to-start key with a thick plastic head and no buttons? Probably a transponder key.
- All-metal key, or a thin plastic head on an older car? Possibly a plain mechanical key.
Still unsure? Give the year, make and model on the phone. That's usually enough for a tech to know which key and which equipment to bring.
Replacing a lost key: what to bring
Programming a key to a car is a security step, so expect identity checks. Ford, for instance, tells owners who want a dealer-made spare to bring a government-issued photo ID and vehicle paperwork showing the VIN and their name, such as a registration, insurance card, title or bill of sale.
- Photo ID
- Registration, title or insurance card in your name
- The car itself, since programming happens at the vehicle
- Any remaining working keys, which may need to be re-registered
One more Ford detail worth knowing: owners who still have two programmed keys can program an additional one themselves using the owner's manual steps. With fewer than two, Ford directs them to a dealer. Other brands have their own rules, so check your manual before you lose the last one.
California's locksmith law covers car keys too: B&P 6980.54 expects a licensed locksmith to be able to copy a vehicle key from an existing one, with Penal Code 466.6 also applying to that work.
If you're down to one key or none, our key fob programming and replacement service can cut and program a new one on site; for a door you can't open, start with a car locksmith visit.
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Frequently asked questions
Can any key shop copy my transponder key?
A shop can cut the metal blade, but the copy won't start the car until its chip is programmed to your vehicle. That step needs programming equipment.
My fob battery died. Can I still start the car?
Often yes. Ford, for example, describes a backup slot that lets an Intelligent Access Key start the car without battery power. Your owner's manual shows where it is on your model.
What do I need to get a new car key made?
Bring a photo ID and paperwork tying you to the car, such as the registration, title or insurance card. Programming is done at the vehicle, so the car needs to be there.
Should I get a spare before I lose my last key?
Yes. Some manufacturers, including Ford, let owners add a key themselves only while they still have two working programmed keys.
