Why can't the Nissan Sylphy be turned off?

[HeidiMarie]

Because the car cannot be turned off, the only way to shut it down during maintenance is to disconnect the battery. Here are some related introductions about stalling: 1. Reasons for stalling: Automatic transmission models: Automatic transmission models do not stall easily, while manual transmission models may stall frequently due to poor driving skills. However, it is not impossible for automatic transmission cars to stall. The main reason is the use of inferior fuel, which causes engine carbon buildup and stalling. 2. Precautions: The stalling phenomenon in automatic transmission cars is mainly caused by the use of inferior fuel. One solution is to go to a regular, large gas station to fill up with high-grade fuel, such as using 97 octane gasoline. Although the price is higher, it can ensure a longer lifespan for your car and better performance during driving.

[KadenMarie]

My Sylphy also had the issue of not being able to shut off the engine a while ago. After struggling for a long time, I found out it was caused by the gear position sensor. This car has a protection mechanism that requires shifting into P gear to turn off the engine. If the sensor gets stuck in D or N gear, turning the key all the way won't do anything. Once on a rainy day when the road was slippery, I didn't push the gear lever all the way when parking, and the P gear light on the dashboard didn't light up. It took me three attempts of pressing the brake and shifting gears to finally turn off the engine. Another possibility is burnt contacts in the ignition switch assembly. My neighbor's car had this issue last year—the key was turned to the OFF position, but the circuit remained active. The ignition switch in the Sylphy is prone to problems and tends to develop poor contact after five or six years of use. Additionally, if the brake light switch fails, the engine control unit won't receive the brake signal and won't allow the engine to shut off. This situation needs immediate repair; otherwise, you'll have to keep your foot on the brake even at red lights. In an emergency, you can pull the fuse to cut power, but this will erase trip data, so it's best to avoid doing this.

[McTheo]

I've studied the circuit diagram of the Sylphy's stalling issue. The root cause is that the ECU doesn't receive the shutdown command. The key component is the rotary ignition switch - oxidized internal copper contacts can cause abnormal conduction. Once I disassembled the switch and found severe carbon buildup on the contacts, which was resolved by sanding them down. The gear position switch also frequently sends false signals, especially during humid seasons. For newer models with electronic shifters, check if the dashboard displays the 'P' gear indicator; if not, try pressing the brake and shifting again. A rare possibility is a faulty Body Control Module causing continuous engine power supply. I recommend using an OBD scanner to read trouble codes: B2790 indicates an immobilizer lock, while U1000 points to CAN communication failure - much more efficient than blindly replacing parts. For vehicles with aftermarket keys, pay attention to the transponder chip - failed OEM authentication will prevent engine shutdown.

[Graham]

Older Sylphy models often fail to shut down due to gear position issues. First check if the P gear indicator light is illuminated on the dashboard. If not, press the brake pedal firmly and shift gears again, and reduce electrical load by turning off AC or headlights if necessary. A sticky ignition switch is the most common cause - noticeable resistance or clicking sounds when turning are telltale signs. As a last resort, try disconnecting the negative battery terminal; this will reset the ECU but forces immediate shutdown. Never forcibly remove the key as it may damage the steering lock. For newer models with start-stop function, be aware that light brake pressure might confuse the auto stop system. Last year my car had a stuck AC fan relay causing continuous power supply that prevented shutdown - replacing the $30 relay fixed it.

[CarolineMarie]

I was once driven crazy by my Sylphy not turning off. Later, a mechanic taught me a detection method: listen for a 'click' sound from the chassis when shutting off the engine - that's the gear lock solenoid valve working. No sound means the signal isn't being transmitted. There are three common failure points: First, there's a microswitch in the gearshift base where aged rubber pads can cause P-gear detection failure. Second, poor contact in the brake switch (the white plastic component above the pedal). Third and most troublesome is deformed contact springs inside the ignition lock cylinder. I temporarily fixed it by spraying carburetor cleaner into the switch gaps. But for long-term use, it's safer to replace the entire assembly - aftermarket parts cost around 300 yuan. Remember to turn off all electrical devices before shutting down, especially dashcams and other additional power-consuming equipment.

[RowanAnn]

Last time at the 4S shop, I saw a Sylphy that couldn't shut off, and it turned out to be caused by an aftermarket dashcam. The modification shop had connected the dashcam to a constant power fuse, causing the ECU to remain powered after the ignition was turned off. Restoring the factory wiring fixed the issue. Normally, the shutdown process requires four signals: key position signal, brake pedal signal, gear position signal, and vehicle speed signal. A running car suddenly unable to shut down is particularly dangerous. I recommend immediately turning on the hazard lights, shifting to neutral, engaging the handbrake, and calling for professional assistance. If handling it yourself, prioritize checking the No. 15 fuse and the IGN relay, as they control the main power supply circuit. Leaving it unaddressed for too long can lead to a drained battery or even damage to the ignition module.