Service Engine Soon Light: What It Means and Whether to Worry
The Service Engine Soon light is different from the Check Engine light. Here is what it means for your specific car.
Service Engine Soon vs Check Engine Light
On most cars, the Check Engine Light and Service Engine Soon light are the same thing with different names. Both indicate that the engine computer detected a problem and stored a diagnostic trouble code. On some vehicles, particularly BMW, Nissan, and some GM models, the Service Engine Soon light specifically indicates a maintenance reminder like an oil change or scheduled service, while the Check Engine light indicates an emission or engine problem. Check your owner manual to know which your car uses.
Common Triggers
The most common cause is a loose or damaged gas cap. Tighten it until you hear it click and drive for a day. The light often turns off on its own. Other common triggers include needing an oil change or scheduled service, a failing oxygen sensor, a catalytic converter issue, a mass airflow sensor problem, or spark plug and ignition coil issues. About 50 percent of the time, it is something inexpensive to fix.
How to Read the Code Yourself
Buy an OBD2 scanner for about 15 to 25 dollars on Amazon. Plug it into the OBD2 port under your dashboard on the driver side. Turn the ignition to the on position without starting the engine. The scanner reads the diagnostic trouble code, which is a letter followed by four numbers like P0420 or P0171. Search the code online for your specific car make and model to see exactly what it means and the typical repair cost.
When to Worry and When Not To
A steady Service Engine Soon light means the issue is not immediately dangerous. You can continue driving but should get it checked within a week or two. A flashing or blinking engine light means a severe misfire that can damage the catalytic converter. Pull over when safe, turn off the engine, and get the car towed to a mechanic. Do not continue driving with a flashing engine light as each minute of driving can cause hundreds of dollars in catalytic converter damage.
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