Check Engine Light Diagnostics in Aurora & Centennial, CO

That little orange light on your dashboard can mean a hundred different things — from a loose gas cap to a serious engine problem. The worst thing you can do is ignore it. The second worst thing is guess. At Keller's Professional Auto & Diesel, we use professional-grade diagnostic equipment to read the codes, pinpoint the issue, and explain exactly what's going on in plain language.

We've been diagnosing check engine lights in the Aurora and Centennial area since 2001. Our ASE-certified technicians don't just pull a code and hand you a parts list — we trace the problem to its root cause so the fix actually sticks.

What Does the Check Engine Light Mean?

Your check engine light is part of your vehicle's onboard diagnostics system (OBD-II). When a sensor detects something outside normal operating range, it triggers a diagnostic trouble code and turns on the light. Common causes include:

  • Oxygen sensor failure — affects fuel efficiency and emissions
  • Catalytic converter issues — can cause reduced performance and failed emissions
  • Loose or damaged gas cap — the simplest fix, but still triggers the light
  • Mass airflow sensor problems — causes rough running and poor fuel economy
  • Spark plug or ignition coil failure — misfires, rough idle, loss of power
  • EVAP system leak — fuel vapor leak in the emissions control system
  • EGR valve malfunction — affects engine performance and emissions
  • Transmission issues — some transmission problems trigger the check engine light

Steady vs. Flashing: Know the Difference

  • Steady check engine light — something needs attention, but you can safely drive to the shop. Don't ignore it, but don't panic either.
  • Flashing check engine light — this means a severe misfire that could damage your catalytic converter. Pull over when it's safe and call for a tow. Continuing to drive with a flashing check engine light can turn a moderate repair into a very expensive one.

Our Diagnostic Process

  1. Read all stored codes using professional scan tools (not the $20 reader from the auto parts store)
  2. Interpret the codes in context — the same code can mean different things on different vehicles
  3. Test the related systems — verify which component is actually failing, not just which sensor tripped
  4. Explain the findings — what's wrong, how urgent it is, and what it costs to fix
  5. Fix it right — backed by our 5-year/50,000-mile warranty

Why Choose Keller's for Check Engine Light Diagnostics?

  • Accurate diagnosis — we find the real problem, not just the code
  • ASE-certified technicians with experience across all makes and models, gas and diesel
  • No pressure — we explain what we find and let you make the call
  • 5-year/50,000-mile warranty on all repairs
  • Family-owned since 2001 — honest work from people who care

Get Your Check Engine Light Diagnosed

Don't let that light stay on. Call us or stop by for a professional diagnosis.

Aurora Location 18385 E Girard Ave, Aurora, CO 80013 Phone: 303-343-9200

Centennial Location 5646 S Gibraltar Way, Centennial, CO 80015 Phone: 720-876-1111

Monday through Friday, 7:00 AM to 5:00 PM. Early bird key drop available.