Diagnostics
Check-engine light diagnosis in Columbus
A code tells us where to start looking, not what to replace. We test until we find the cause, write it down for you and give you a price before any repair.
Explained
What the check-engine light is telling you
Every car and light truck sold in the US since the 1996 model year has an on-board diagnostic system, known as OBD-II. It watches the engine, fuel and emissions systems, and when a reading falls outside its limits it stores a trouble code and switches on the amber, engine-shaped light on your dashboard.
That one light covers hundreds of possible faults, from a gas cap that is not sealing to a worn-out catalytic converter. What matters first is how it is lit.
Common causes we find on Columbus cars: loose or worn gas caps, oxygen sensors, worn spark plugs or ignition coils, small leaks in the evaporative (EVAP) system, cracked vacuum hoses and tired catalytic converters.
Solid light. A fault has been stored. The car is usually fine to drive for now. Book a diagnosis in the next few days.
Flashing light. A severe misfire that can overheat and ruin the catalytic converter. Slow down, avoid hard acceleration and come in today.
The flashing lamp above blinks once a second. With reduced motion turned on, it is marked with a dashed outline instead.
Code vs. cause
Why a code is not a diagnosis
A free code read at a parts store gives you something like P0171, “system too lean”. That means the engine is getting too much air or too little fuel. It could be a vacuum leak, a dirty airflow sensor, a weak fuel pump or a leaking injector.
Swapping parts until the light goes out gets expensive fast. Testing first is cheaper, and it fixes the car the first time.
Diagnosis from $99. If you go ahead with the repair here, the fee comes off the bill.
How we diagnose
- Ask when the light came on and what the car is doing
- Scan every module and read the freeze-frame data saved when the fault happened
- Check the maker’s service bulletins for known problems
- Test the suspects: smoke test for leaks, scope for sensors and coils, fuel pressure
- Write up the findings with photos and a repair estimate
- After the repair, clear the codes and road test to confirm the fix
Dashboard guide
Other dashboard warning lights
Choose a light to see what it means and how soon to act. As a rule, red means stop soon and amber means book a visit.
Check-engine light
Book within a few daysWhat it means: The engine computer has stored a fault in the engine, fuel or emissions system.
What to do: If it is solid, book a diagnosis. If it is flashing, slow down, avoid hard acceleration and come in today.
Oil pressure
Stop safelyWhat it means: Oil pressure is too low to protect the engine. This is not the oil-change reminder.
What to do: Pull over, switch off and check the oil level. Do not drive on it; call us and we will arrange a tow.
Battery and charging
Head to us nowWhat it means: The charging system is not keeping the battery charged, often an alternator or belt problem.
What to do: Switch off the heater, radio and other extras and drive straight to the shop. The car may stall once the battery runs down.
Engine temperature
Stop safelyWhat it means: The engine is overheating.
What to do: Pull over and switch off. Do not open the radiator cap while it is hot. Driving on can warp the cylinder head.
Brake system
Check nowWhat it means: The parking brake is on, the brake fluid is low, or the brake system has a fault.
What to do: Make sure the parking brake is fully off. If the light stays on, have the brakes checked before you drive far.
ABS
Book this weekWhat it means: The anti-lock braking system has a fault and has switched itself off. Normal braking still works.
What to do: Drive with extra care on wet or icy roads, and book a diagnosis.
Tire pressure (TPMS)
Check todayWhat it means: One or more tires are at least 25% below the recommended pressure. If it flashes first and then stays on, a sensor has a fault.
What to do: Check the pressures with a gauge and inflate to the door-jamb figure. Cold Ohio mornings often set it off.
Traction control
Keep an eye on itWhat it means: Flashing means the system is working to stop wheelspin. Staying on means it is switched off or has a fault.
What to do: Flashing on slippery roads is normal. If it stays on, book a check.
Symbols vary a little between makers. Your owner’s manual shows the exact ones for your car.
FAQ
Questions we hear at the counter
Can I drive with the check-engine light on?
If the light is solid and the car drives normally, usually yes, for a short while. Book a diagnosis within a few days. If the light is flashing, or the car is shaking, losing power or smells hot, slow down and get it to us the same day.
Will the light go off on its own?
Sometimes. After a loose gas cap or a one-off fault, the light can go out after several drives once the system re-checks itself. The code stays in memory, though, and a light that comes back means the problem is still there.
What does a diagnosis cost?
Diagnosis starts at $99 for about an hour of testing. Some intermittent faults need longer, and we call you before going past the first hour. If you approve the repair, the diagnosis fee comes off the bill.
Light on right now?
Book a diagnosis online, or call if the light is flashing and we will fit you in.