When the check engine light pops up on your dashboard, it’s your car’s way of saying, “Something’s wrong—please check me out.” Sometimes it’s minor, like a loose gas cap. Other times, it’s a serious issue that can damage your engine or catalytic converter if you keep driving.

At RPM Automotive in Prairie du Chien, WI, our ASE-trained technicians use advanced diagnostic equipment to quickly pinpoint what triggered the light and what needs to be fixed so you can get back on the road safely and confidently.

What Your Check Engine Light Might Be Telling You

Your vehicle’s onboard computer constantly monitors sensors and systems throughout the car. When it sees something outside of normal operating range, it stores a trouble code and turns on the check engine light.

Common issues that can trigger the light include:

• Loose or faulty gas cap

• Failing oxygen (O2) sensor

• Mass airflow (MAF) sensor problems

• Faulty ignition coils or spark plugs

• Catalytic converter issues

• Fuel system or evaporative emissions (EVAP) leaks

• Engine misfires

• Transmission-related faults

Some of these are relatively minor if caught early. Others can lead to expensive damage or poor fuel economy if ignored.

Solid vs. Flashing Check Engine Light

Not all check engine lights mean the same thing:

• Solid check engine light
  Typically means a non-emergency issue is present. You should schedule a diagnostic as soon as possible, but you can often drive the car cautiously if it feels normal.

• Flashing check engine light
  Indicates a more serious problem—often an active misfire that can quickly damage your catalytic converter. In this case, it’s best to stop driving, have the vehicle towed, and let our technicians inspect it immediately. 

If you’re not sure which type you’re seeing or the car feels “off,” play it safe and call us.

What To Do When Your Check Engine Light Comes On

• Check your gas cap and tighten it until it clicks.
• Pay attention to performance—any rough running, hesitation, or loss of power is important.
• Avoid hard acceleration until the issue is inspected.
• Schedule a diagnostic at RPM Automotive.
• If the light is flashing, stop driving and call for guidance.

Our Check Engine Light Diagnostic Process

At RPM Automotive, we don’t just “clear the codes and hope for the best.” We follow a thorough, step-by-step diagnostic approach to fix the issue the right way:

• Customer Interview & Road Test
  We ask about when the light came on, how the car has been behaving, and any recent repairs. When needed, we perform a test drive to duplicate symptoms.

• Computer Scan & Code Retrieval
  Using professional-grade scan tools, we access your vehicle’s onboard computer, retrieve trouble codes, and capture live data from sensors. 

• System & Component Testing
  Trouble codes tell us where to look, not exactly which part to replace. We verify the root cause using tests such as:

  • Sensor and wiring checks

  • Fuel and ignition system tests

  • Smoke testing for EVAP or vacuum leaks

  • Compression or leak-down tests when needed

• Accurate Estimate & Repair Plan
  Once we find the cause, we’ll walk you through what’s wrong, what needs to be done, and how much it will cost—before any repairs are completed.

• Quality Repairs & Verification
  We perform the necessary repairs, re-check the system, clear codes, and road-test the vehicle to confirm the issue is fully resolved.

• 3-Year / 36,000-Mile Nationwide Warranty
  All qualifying repairs are backed by our 3-year, 36,000-mile nationwide warranty, recognized at ACDelco service centers across the country. 

Frequently Asked Questions About the Check Engine Light

How serious is a check engine light?
It depends on the cause. Some issues are minor (like a loose gas cap), while others can quickly damage expensive components or create a safety risk. Any time the light is on, you should have it checked—especially if you notice performance problems or if the light is flashing.

Can I keep driving if the check engine light is on?
If the light is solid and the car feels normal, you may be able to drive short distances, but you should schedule a diagnostic soon. If the light is flashing, the engine is running rough, or there are strange smells/noises, you should stop driving and call us for advice.

Will a parts store code reader tell me exactly what’s wrong?
Generic code readers can give you a basic trouble code, but they don’t provide the full picture. A code like “O2 sensor fault” doesn’t always mean the sensor itself is bad—there could be wiring, fuel trim, or exhaust issues causing the code. Our technicians use advanced tools and testing procedures to find the actual root cause and prevent unnecessary parts replacement. 

How long does a check engine light diagnostic take?
Simple issues can sometimes be diagnosed relatively quickly, while more complex problems may require more time for testing and verification. We’ll keep you updated on what we find and how long repairs will take.

Will the check engine light reset itself?
In some cases, if the condition that caused the light goes away, the computer may turn the light off after a certain number of drive cycles. However, the stored code and issue history remain. Even if the light goes off, it’s smart to have us scan and check the system to make sure there isn’t a lingering problem.

Schedule Your Check Engine Light Diagnostic Today

If your check engine light is on, don’t wait for a small problem to turn into a big repair bill.

RPM Automotive
1519 S Marquette Rd
Prairie du Chien, WI 53821
Phone: (608) 527-0377 

Call today or stop by to schedule a professional check engine light diagnostic. Our team will find the problem, explain your options clearly, and help you get back on the road with confidence.