Your check engine light is a signal from the engine control module that one of the dozens of sensors in your vehicle has reported something outside expected range. It could be a loose gas cap that throws an evap-system code. It could be a failing oxygen sensor. It could be a misfire that's actively damaging your catalytic converter. The light alone doesn't tell you which — that's what proper diagnostic equipment is for. Frank's Automotive in New Braunfels reads the codes, interprets them with context, and tells you what's actually happening.
What's involved
A check-engine-light diagnostic at our shop:
- OBD-II scan with a Bosch professional scan tool — pulls active and pending diagnostic trouble codes (DTCs) plus freeze-frame data
- Live data analysis — we watch sensor readings (fuel trim, mass airflow, oxygen sensors, coolant temp) while the engine runs, looking for what's outside spec
- Visual inspection — a code points to a system, not a part. P0171 (lean fuel) could mean a vacuum leak, dirty MAF sensor, weak fuel pump, or clogged injector. We check before condemning a part
- Targeted testing — smoke test for vacuum leaks, fuel pressure test, injector flow, sensor signal on a scope, compression test if the code suggests internal problems
- Written diagnosis — you get the code, what it means, what we found, and what it costs to fix
We never just clear the code and tell you it's fixed. Clearing a code that points to a real fault is how a $200 sensor becomes a $1,500 catalytic converter.
When to bring it in
The two states of the check engine light matter:
- Solid (steady) light — there's a fault, but the vehicle is safe to drive in the short term. Schedule within a week or two. Common causes: O2 sensor, evap leak, EGR valve, mass airflow sensor
- Flashing light — active misfire dumping raw fuel into the catalytic converter, which can destroy a $1,200 part in 30 miles. Pull over and don't drive further — call us and we'll arrange a tow
Other reasons to come in: light came on then off (the code is still stored — we can read pending codes); reduced power with the light (ECM in limp mode); failed emissions inspection (Texas requires annual in many counties).
Why Frank's for check engine light
Our service techs are ASE Certified and we're a Bosch Service Center with the same OBD-II scan tools and software the dealerships use. Cheap code readers from a parts store give you the DTC number; we give you what it means in your specific vehicle's context. The diagnosis and repair are covered by our 24-month / 24,000-mile warranty.
If the dashboard light is steady, schedule normally; if it's flashing, call now — (830) 627-3939 — and we'll get the vehicle off the road. Request an appointment for a non-emergency diagnostic.