Understanding the Difference Between the Check Engine Light and the Service Engine Soon Light 

Modern vehicles are equipped with advanced computer systems that constantly monitor performance, emissions, and maintenance needs. Two of the most misunderstood dashboard alerts are the Check Engine Light and the Service Engine Soon (or Service Due) Light. While they might look similar, they serve very different purposes. 

Service  

Service Due / Service Engine Soon Light 

What It Means: 

This light is a reminder for routine maintenance, triggered by mileage or time-based service intervals. Depending on the make and model, it may appear as: 

• “SERVICE DUE” 
• “SERVICE ENGINE SOON” 
• “Service A/B/X/Y” (e.g., in Mercedes-Benz vehicles) 

Common Services It May Indicate: 

• Oil change 
• Air filter replacement 
• Cabin filter replacement 
• Brake fluid flush 
• Tire rotation 

What To Do: 

Take a deep breath—this light is not an emergency. However, don’t ignore it. Schedule your maintenance appointment soon to keep your vehicle in top condition. Our team at NavAuto1 Group can quickly assess and take care of the services your vehicle needs. 

Pro Tip: Staying current with routine maintenance helps prevent breakdowns and future check engine light issues. It’s a crucial part of keeping your car reliable and road ready. 

Check Engine Light (CEL) What It Means: 

The check engine light indicates a malfunction in your vehicle’s engine, emissions, or powertrain system. It usually shows up as an engine icon and may include messages like “CHECK” or “CHECK ENGINE.” 

Common Triggers: 

• Loose or damaged gas cap 
• Faulty oxygen sensor 
• Failing catalytic converter 
• Spark plug or ignition coil issues 
• Mass airflow sensor failure 
• Cylinder misfire 
• Emissions system leaks 

Did You Know?

Even something simple—like refueling with the engine running—can trigger the light due to emissions sensors detecting a “leak.” 

What To Do: 

• If the light is flashing, stop driving and seek immediate service. This could indicate a serious misfire that may damage the catalytic converter. 
• If the light is solid, schedule a diagnostic as soon as possible. Even if the vehicle feels fine, hidden damage can worsen over time. 

Avoid guessing or DIY fixes. Improper repairs can lead to more damage and higher costs. Our certified technicians at NavAuto1 Group use advanced diagnostic tools to accurately identify and fix the issue. 

One Light for Both? 

In some vehicles, one light may serve dual purposes, acting as both a maintenance reminder and a system warning. If you’re unsure which it is, check your owner’s manual or let our team look at it for you. 

Trust NavAuto1 Group for Accurate Diagnostics & Maintenance “COMPUTER DIAGNOSTIC”

Whether your dashboard is calling for a service visit or signaling a deeper issue, the ASE-certified technicians at NavAuto1 Group are here to help with: 

• Advanced diagnostics 
• Fast, same-day service 
• Dealer-level capabilities 
• Honest, transparent explanations 
• Long-term solutions, not quick fixes 
• Our team of ASE-certified technicians undergoes over 60 hours of manufacturer-specific training each year to stay up to date with the latest OE (Original Equipment) advancements and repair techniques. We utilize cutting-edge diagnostic tools and industry-leading repair methods to ensure the job is done right the first time.  

Call us or schedule your appointment online today. We’ll get you back on the road with confidence and peace of mind.