Here's what you should do:
1. Identify the Problem: The first step is to find out *why* the SES light is on. You can do this in a few ways:
* OBDII Scanner: This is the best approach. An OBDII scanner (available at most auto parts stores) plugs into your vehicle's OBDII port (usually under the dashboard) and reads the diagnostic trouble codes (DTCs). These codes pinpoint the specific problem. You can then search online for the meaning of the codes.
* Advanced Scanners: Some scanners offer more detailed information and even guide you through potential repairs.
* Auto Parts Store: Many auto parts stores will scan your vehicle's codes for free.
2. Address the Problem: Once you know the DTCs, you can research the likely cause and repair it. This might involve:
* Simple Fix: Sometimes it's something minor like a loose gas cap (a common cause).
* Repair: The problem might require replacing a sensor, fixing a leak, or more extensive repairs. Consider taking it to a mechanic if you're not comfortable doing repairs yourself.
3. Reset the SES Light (After Repair): *Only after you've addressed the underlying problem* should you reset the SES light. There are several ways to do this:
* OBDII Scanner: Most OBDII scanners have a function to clear trouble codes.
* Disconnect the Battery: Disconnect the negative terminal of your battery for about 15-20 minutes. This will often reset the light, but it's not guaranteed to work for all codes. Note: This will reset other vehicle settings, such as radio presets.
Important Considerations:
* Ignoring the light is dangerous. Driving with a malfunctioning system can lead to further damage, reduced fuel efficiency, and potentially unsafe driving conditions.
* DIY vs. Professional Repair: If the problem seems complex or involves intricate engine components, it's best to take your E250 to a qualified mechanic.
In short: Don't just reset the light. Find out what caused it and fix the problem first. Then, you can reset the light.
