What are the reasons why a BMW 520 won't start?
3 Answers
There are several reasons why a BMW 520 may not start, including battery power, fuel level, and coolant issues. Insufficient battery power: This could be due to a drained battery from leaving headlights on for an extended period or an expired battery lifespan. It is generally recommended to replace the battery every 2 years. Additionally, installing xenon headlights, high-power audio systems, or DVD players can also cause electrical circuit failures in the vehicle. A simple way to check if the vehicle has power is by pressing the car horn. Low fuel level: If the fuel gauge shows the level below the red line, the car naturally won't start. It's also important to pay attention to fuel quality. Owners should always refuel at reputable gas stations. When traveling, carrying a gauze to wrap around the fuel nozzle can help filter out impurities. Lack of antifreeze: Some owners use water or low-quality antifreeze, which can lead to the entire cooling system freezing in extremely cold winter conditions. This can cause the engine to crack, prevent the car's water pump from functioning, result in failure to start, and damage other engine components.
As a seasoned BMW driver with over a decade of experience, my 520 has also encountered starting issues, which can stem from various common causes. The primary culprit is often a weak battery, especially in winter when low temperatures slow down battery discharge—if the dashboard lights don't come on, that's a clear sign. I once resolved it by jump-starting the car myself, which was hassle-free. Another frequent issue is a faulty starter motor; if you hear a clicking sound when turning the key but the car doesn't move, the motor might be stuck or worn out. Ignition system failures, such as heavily carbon-fouled spark plugs or loose ignition coils, can also lead to insufficient spark and failure to start. Fuel system problems, like a failing fuel pump or clogged filter, can prevent fuel delivery and starting. BMWs are also prone to electronic system glitches, such as the ECU falsely reporting error codes. For safety, regularly check battery life and keep terminals clean, and pre-warm the engine in extreme cold. If the car won't start, don't force it—first try simple fixes like checking battery connections, and if that doesn't work, call a professional tow service. BMW service centers have advanced diagnostic tools for quick fixes, so don't cut corners and risk bigger issues.
When encountering a 520 model that won't start, professional analysis is required. Battery issues are common - if voltage tests below 12V, replacement is needed. Starter or alternator failure can also cause this; if the engine cranks normally but doesn't start, check for relay burnout. BMW models with multiple electronic controls may experience fuel delivery issues from dirty throttle bodies or disrupted ignition signals from faulty MAF sensors. Low fuel pump pressure is another risk, especially with low fuel levels. I recommend using an OBD scanner to quickly identify trouble codes rather than risking wire damage through disassembly. For safety, ensure proper ventilation to prevent spark hazards. Regular maintenance extends component lifespan - replace batteries every two years and clean fuel systems. Keep electronic components like ECUs updated, but avoid risky wiring modifications. When troubleshooting no-start conditions, methodically check simple causes before investigating complex faults.
