Can a Spare Key Start a Car?

[OLena]

Spare keys can start a car. The method to use a spare key is: 1. Locate a small rectangular hole at the end of the car handle and pull the handle outward; 2. Insert the spare key into the rectangular hole to remove the lock cover; 3. Use the spare key to unlock the car door. Precautions for using the key include: 1. Avoid contact with objects that have magnetic fields; 2. Avoid exposure to high-temperature environments; 3. Avoid hanging it together with other keys or accessories; 4. If lost, promptly match a new key to prevent property loss; 5. Avoid placing the spare key inside the car; 6. Prevent the smart key from dropping or being impacted; 7. When replacing the key battery, ensure the battery model matches.

[GarrettLynn]

Of course it can start the car, my spare key has saved me in a pinch! During that trip when I lost my main key, luckily the spare was in the glove compartment. Just insert it into the ignition switch, give it a twist, and the engine starts. But a reminder: spare keys usually only have basic functions—mine doesn’t have a remote unlock button, though it does have an anti-theft chip. For long-term use, be cautious: some cars trigger an anti-theft alarm if the spare key is used for more than two weeks, with a yellow lock symbol lighting up on the dashboard. Remember to check the spare key’s condition regularly. Last time, my family’s spare key sat unused for five years, and the battery leaked, corroding the circuit board. Ended up costing 800 yuan to replace it—really not worth it.

[Juan]

It can start, but it depends on the key type. For older cars with mechanical keys, you can use them freely—like the spare key for my 2006 Jetta, which can directly open the door and start the engine. Keys with chips are more complicated: last week, my neighbor's Hyundai started with the spare key, but the steering wheel locked, and they had to go to the dealership to unlock it. Nowadays, spare keys for smart keys are usually foldable mechanical keys hidden in the key fob, which can only be used to open the door and turn the ignition. The most troublesome are keyless start models—when the spare key runs out of battery, you have to place it near the steering wheel's sensor area to start the car. I once encountered this situation on a business trip and almost missed my flight. It's recommended to replace the spare key's battery every quarter to avoid last-minute issues.

[StAlana]

The car can start, but the experience is compromised. I have two car keys, and the spare one is noticeably slower—it requires an additional 15-degree turn in the ignition switch to power on. The 4S shop said it's due to wear and tear on the lock cylinder. Modern car spare keys often have limited functionality: for example, in my Sonata, the automatic headlights and wipers don't work when using the spare key. Also, beware of anti-theft traps: a friend's French car had its ECU locked after three consecutive starts with the spare key, costing 500 in towing fees. Most importantly, pay attention to the key's age—the rubber handle on the spare key can age and break after seven years, so now I protect it with a silicone cover.