Our Simple Three-Step Process
From your appointment request through repair authorization, we keep the diagnostic process clear and documented.
1. Schedule Your Appointment
Choose an appointment time so we can evaluate the warning light and any performance symptoms you’ve noticed.
2. Review the Findings
Our technicians complete the necessary diagnostics and inspections before making recommendations. We send your Digital Vehicle Inspection report and estimate by text, allowing you to discuss the findings with a service advisor or approve the recommendations through the report.
3. Authorize the Repair
We perform or schedule only the work you approve. If we recommend additional service, you receive the findings and estimate before deciding how to proceed.
1. Schedule Your Appointment
Whether scheduling online or over the phone be sure and let us know what you're experiencing so we can provide fast and accurate service advice.
2. Diagnostics and Inspections
Drop off your vehicle and the shop will get to work with inspections and diagnostics using the same equipment as the manufacturers to determine issues and next steps.
3. Digital Vehicle Inspection Report and Estimate
Following the diagnosis we will text you a digital vehicle inspection report, containing pictures and videos of our findings and recommendations.
4. Review and Approval
A service advisor will reach out to walk you through the findings and recommendations to determine how you would like to proceed, or you can approve work directly in your DVI.
5. Work Performed or Scheduled
Most work can be completed immediately, or scheduled based on parts and customer availability.
Can You Drive with the Check Engine Light On?
What you should do depends on whether the light is steady or flashing and how the vehicle is running. A steady light requires prompt diagnosis, especially when it appears with rough running, hesitation, or reduced power.
If the light flashes, reduce your speed and seek service promptly. A flashing warning commonly points to an active misfire or another urgent fault. If the vehicle is shaking, losing power, overheating, or otherwise unsafe to operate, stop driving when it’s safe to do so.
Your vehicle’s onboard diagnostic system stores trouble codes when it detects problems involving sensors or actuators. Checking those codes is an important first step, but live data and component testing are needed to determine what caused the warning.
What Full Service Diagnostic Testing Actually Involves
Modern vehicles store fault codes in the engine control unit (ECU) when sensors detect a problem. Reading those codes is the starting point, not the conclusion. Our Full Service Diagnostic Testing goes further: live data analysis, component testing, and a hands-on physical inspection to confirm the root cause behind any stored code.
Throughout the process, our Digital Vehicle Inspection captures photos of your vehicle so you can follow what our technicians find. Before any repair moves forward, we explain the findings in plain terms, answer your questions, and get your approval. We use manufacturer-quality equipment throughout, and nothing is performed without your authorization.
Performance Symptoms That Need Diagnosis
A dashboard warning can be accompanied by other signs of a problem. Rough idling, hesitation, hard starting, or a noticeable loss of power can indicate that the detected fault is affecting how the vehicle runs.
Other symptoms to report when scheduling include:
- Transmission slipping or delayed shifting
- Dragging brakes or resistance while driving
- Reduced fuel economy
- Engine shaking or misfiring
- Unusual odors or exhaust smoke
Vacuum hose leaks, ignition timing problems, and worn or fouled spark plugs can contribute to drivability concerns. Telling your service advisor when the symptom occurs, such as during acceleration, at idle, or after a cold start, gives our technicians useful context for testing.
Common Reasons Your Check Engine Light Is On
A check engine light can point to dozens of conditions. These are the causes we see most often:
- Loose or damaged gas cap: A poor seal creates a pressure leak in the evaporative emissions (EVAP) system and stores a fault code.
- Failing oxygen sensor: Oxygen sensors monitor exhaust composition so the engine computer can regulate the air-fuel mixture. A worn sensor reduces fuel economy and can eventually damage the catalytic converter if left unaddressed.
- Worn spark plugs or ignition coils: These can cause engine misfires that the computer detects immediately. A flashing check engine light often means an active misfire is occurring and warrants prompt attention.
- Failing mass airflow (MAF) sensor: The MAF sensor measures air entering the engine. When it fails, drivers typically notice rough idling, hesitation, or hard starting.
- Catalytic converter degradation: Deterioration is usually the result of an unresolved upstream issue, such as a prolonged misfire or a faulty oxygen sensor. That’s why thorough diagnosis before replacement is essential.
Additional causes:
- Fuel system issues: Failing fuel injectors or a faulty fuel pressure regulator can store codes and affect drivability, including rough idle or loss of power.
- EVAP system faults beyond the gas cap: Cracked hoses, failed purge valves, or vent valve failures can trigger persistent EVAP codes. Locating these leaks typically requires smoke or pressure testing.
Steady Light vs. Flashing Light
A steady check engine light indicates a condition that should be diagnosed soon. You can generally keep driving if the vehicle is otherwise operating normally, but don’t put off scheduling service. A flashing light signals an active misfire or urgent fault. Reduce your speed and seek service as soon as possible to avoid damage to the catalytic converter or other components.
Check Engine Light & Colorado Emissions Testing
Highlands Ranch is within Colorado’s designated emissions inspection area. As of 2026, an illuminated check engine light causes an automatic failure of the onboard diagnostics portion of an emissions inspection, regardless of the vehicle’s tailpipe results. The light must be addressed and cleared before the vehicle can pass.
Model year 1982 and newer vehicles are generally inspected every two years, while 1981 and older vehicles are inspected annually. New vehicles are exempt for their first seven model years, and all-electric vehicles are exempt from Colorado emissions testing requirements. Staying current on scheduled maintenance, including spark plug replacement, air filter changes, and fuel system service, can help address problems before an inspection is due.
Your Local Christian Brothers Amenities
FAQs
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Q. "What is the difference between a steadily lit and a flashing check engine light?"A steadily lit light means that a sensor is sending a signal to your vehicle's computer that something is wrong or it could simply mean that the sensor is out. If your check engine light is flashing, however, that means there is a serious issue and you should stop driving immediately.
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Q. "Why is my check engine light on but nothing seems to be wrong with my vehicle?"If nothing within your vehicle stands out, then it is possible that it is just a minor issue such as a loose gas cap or a bad O2 sensor. It is still recommended to see a mechanic if the light doesn't disappear to check for any larger issues.
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Q. "Do you offer a warranty?"As part of our Nice difference.® commitment to providing our customers the best auto service experience possible, we also offer a3-year/36,000-mile warranty on all the work that we do. We offer this warranty at every Christian Brothers Automotive nationwide, and it will be honored at any location, regardless of which branch did the initial work.
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Q. "Can you provide service under my extended warranty?"Yes. At Christian Brothers Automotive, we work with all major extended warranty providers to make needed repairs for our customers. If you have an extended warranty, you can discuss your carrier with our team when scheduling an appointment and confirm that the work will be covered. You can find a partial list of the extended warranty companies we work with here.
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Q. "What to do if your check engine light turns on?"We recommend heading to your local auto shop as soon as you are able. This is typically a sign that there is an abnormality within your engine.
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Q. "Is it safe to drive your car when the check engine light is on?"It depends. If you are experiencing other noticeable issues with your vehicle, it may be best to pull over. Otherwise, it is typically okay to drive to your local auto shop. You will want to get this checked sooner rather than later to avoid being stranded with a broken-down car.
Have more Questions?
Our friendly auto service experts have the answers.
Call your local Christian Brothers Automotive car shop today
Hear What Our Customers Had to Say About Us
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"Yesterday was my first visit to Christian Brothers. Will, the Service Writer, extended his hand to shake mine. He greeted me in a warm, friendly manner. His demeanor extended to taking my information in a knowledgeable, efficient way. He took time to know "
- Frank