Why is the car locked and unable to start?

[McSavannah]

When a car is locked and unable to start, it indicates the vehicle is equipped with an engine electronic anti-theft system, also known as a transponder-based immobilizer. Its fundamental principle is to lock the car's engine, electrical circuits, and fuel system, preventing the vehicle from starting without a chipped key. A locked car anti-theft system is a common malfunction of vehicle anti-theft devices. Relevant explanations are as follows: 1. The car has an engine electronic anti-theft system, which only allows the vehicle to start when the chip inside the key matches the code in the anti-theft system. 2. The spare key does not contain a chip, hence it cannot start the car. The spare key can only be used to unlock the door when the original key is lost.

[DiFelix]

I've been driving a taxi for nearly twenty years and encountered car lock situations at least dozens of times. The most common is the steering wheel mechanical lock—it jams when you accidentally turn the wheel while shutting off the engine. I remember one early morning dropping off a passenger; in a hurry, I turned off the engine, and the key just wouldn’t budge. Turns out, gently wiggling the steering wheel with the left hand while turning the key with the right hand did the trick. Then there’s the issue of remote key fobs running out of battery—I had three cases in a row last year, with the anti-theft light on the dashboard flashing like crazy. Just replacing the coin battery fixed it. And then there are those rookie mistakes like not shifting to P in an automatic or not pressing the clutch in a manual—new drivers are especially prone to these. Last month, a young guy in my fleet even had to call a tow truck because the floor mat got stuck under the clutch pedal, costing him a pointless 500 bucks.

[BradleyFitz]

The repair shop receives two to three vehicles with lockout failures every day. These issues generally fall into three categories: anti-theft system failures, mechanical lockouts, and electrical circuit problems. Anti-theft lockouts are mostly caused by dead key fob batteries or signal interference, such as parking near high-voltage power lines. Mechanical locks commonly involve steering wheel lockouts or gearshift lever lockouts, with BMW's electronic gearshift being particularly troublesome—requiring specialized computer reset. As for electrical faults, most are due to dead batteries or blown fuses. Last week, an old Accord had its starter relay short-circuited due to water ingress, causing the anti-theft module to crash. The most troublesome issue is when the engine anti-theft matching fails, requiring a reflash of the ECU program. It's recommended that car owners always keep a spare key and avoid forcefully turning the steering wheel when parked.

[DeAlice]

As a female car owner, what I fear most is unexpected situations. Last week when I came back from shopping, I found the steering wheel locked, and I was so anxious that my palms were sweating. Later, I called the 4S store, and the after-sales service taught me to gently turn the steering wheel left and right while turning the key, and it indeed unlocked. Another time, the remote key failed—it turned out the signal interference in the supermarket parking lot was too strong. Now, I always carry a mechanical key as a backup. Sisters in the car owners' group reminded me that for automatic transmissions, you must shift to P (Park) before turning off the engine, as one friend forgot to shift gears and caused a complete power failure. Also, car batteries are prone to losing charge in winter, so it's best to check the voltage monthly. If you encounter a lock, don’t force it, or you might end up paying more for lock repairs.