What Are the Reasons Why the Car Key Can Open the Door but Cannot Start the Car?
4 Answers
Specific reasons are introduced as follows: 1. Gear position reason. If the car is not parked in the P gear, most vehicles nowadays will display a reminder on the central control dashboard, and some may also have a buzzer sound as a reminder. Therefore, the probability of this situation occurring is very small. Usually, it happens when the driver hastily turns off the engine in D gear and then leaves the car. When getting back into the car, the driver may overlook this issue. 2. The car key cannot be turned, making it impossible to start the vehicle, and the steering wheel is also locked. After parking, turning off the engine, and removing the key, if the steering wheel is moved again, the steering lock and steering column will automatically engage, thereby locking the steering wheel as an anti-theft measure. To unlock the steering wheel, simply turn it slightly in the original direction while turning the key. Additional information: Signs of car battery failure: The car battery indicator light turns on or the battery bulges. This is the most common and intuitive sign. When the car battery warning light on the dashboard illuminates, the owner must take it seriously.
I encountered the same issue a few days ago—the door locks worked, but there was no response when trying to start the car, which was really frustrating. My first thought was that the key fob battery was dead. My car has a smart key with an internal battery; if the battery runs out, the car won’t recognize the start signal. Then, I checked the car battery itself—if it’s low on power, it won’t have enough juice to crank the engine. Next, I suspected a faulty start button or ignition switch, as older buttons can stick or wear out over time. I also recalled one instance where the anti-theft system inexplicably locked the engine, requiring a key reprogramming. Ultimately, the problem turned out to be a parasitic drain from the charging system, which depleted the battery. To avoid this, I recommend regularly checking and replacing the key fob battery every year or two, and ensuring the car battery doesn’t sit discharged for too long—otherwise, you’ll end up spending unnecessarily on a new battery, which is far cheaper than repairing a starter. For safety, don’t delay—get it checked by a mechanic right away.
As a car enthusiast, let me break down this issue for you. The key can unlock but fails to start the car, and the crux lies in electronic signal matching. Your car key emits an RFID signal – if the coin cell battery inside the key is running low, the vehicle's ECU won't receive the decoded signal, interrupting the starting procedure. Another scenario is when the car's main battery is dead: the door lock motor requires minimal power and may still function, but starting demands high current that simply can't be sustained. Sometimes the problem hides in the starting system, like oxidized internal contacts in the ignition switch causing poor connectivity. I've also heard cases of loose or corroded battery terminals disrupting current transmission. Preventive measures include periodically checking battery voltage with a multimeter to maintain it above 12 volts, or observing whether the key's signal indicator light blinks (blinking confirms signal operation). Prolonged parking in humid environments accelerates rust formation, affecting component connections – proper maintenance can prevent such unexpected failures.
Encountering a situation where the car door unlocks but the vehicle won't start is quite common, and there could be several reasons. For instance, the key fob battery might be dead—try replacing it with a new CR2032 battery. Insufficient charge in the car's main battery is another major cause; door locks require minimal power, but starting demands high current. Additionally, a damaged start button or ignition knob, or accumulated dirt on the contacts, could lead to failure. There might also be an issue with the anti-theft system, where the car refuses to start if it doesn't recognize the key. When troubleshooting, start with the simplest solutions: replace the key battery or jump-start the car battery. Regular maintenance should include checking these components to save time and money. Always prioritize safety—avoid forcing the start to prevent damaging the motor.
