Symptom guide
Check engine light on? Steady or flashing matters
A steady light means the car has stored a fault and wants it looked at soon. A flashing light means a misfire is happening right now. Those are two very different levels of urgency.
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Narrow it down
What it usually means
Steady light, car drives normally
A fault has been stored. It might be minor, like a gas cap that isn't sealing, or the early sign of something bigger. Book a scan soon, and don't let the light become the new normal.
Flashing light
An active misfire is sending unburned fuel into the exhaust. Ease off, get somewhere safe and park. Driving on can overheat and damage the catalytic converter.
Light plus a rough idle or shaking
Misfire territory: spark plugs, coils, injectors or, on some engines, a known mechanical fault. On 2019–2021 GM 5.3 and 6.2 V8s, collapsed lifters are a documented cause. More on Chevrolet.
Light plus less power
The car has gone into a protective mode. On a VW or Audi you may see the EPC light too. On a BMW, "Drivetrain malfunction". Drive gently and keep it off the interstate until it's been scanned.
Light plus a rattle on cold starts
A brief rattle at start-up, with cam timing codes stored, often points to worn cam phasers or timing chain parts. It's well known on Ford's 3.5 EcoBoost and GM's 3.6 V6, among others.
Light came on right after you filled up
Check that the gas cap is tight and clicked. If that was it, the light can take several drives to go out by itself. If it stays on, get it scanned.
A guide, not a diagnosis. Two cars with the same symptom can have different faults, which is what testing is for.
Worth knowing
Before you spend money
- Don't clear the code before we see it. The stored data shows when and how the fault happened.
- A free code read names a circuit, not a part. Testing finds the part. How our diagnostic works.
- Note what changed: a fill-up, heavy rain, a hard pull onto the interstate, a cold start.
- A dash full of warnings at once is often a voltage problem. Start with the battery and charging.
Questions
Asked about this one
Is it safe to drive with the check engine light on?
If it's steady and the car drives normally, usually yes, for a short while. Book a scan soon. If it's flashing, or the car is running badly, ease off and park.
Will the light go off by itself?
Sometimes, if the fault was temporary, like a gas cap that wasn't tight. If it stays on or keeps coming back, the cause is still there.
How much is a check engine light diagnosis?
$125, and it goes toward your repair if we do the work. We scan every module, not just the engine.
Other symptoms
More guides
Car won't start
Click, slow crank or nothing at all? What each one usually means, and what to check first.
Brakes squealing or grinding
Squeal, grind or shudder. What the noise usually means, and how soon to book.
Battery light on
The battery light usually means the car isn't charging. What to do on the road, and what we test.
Still not sure what it is?
That's what the diagnostic is for. $125, and it goes toward your repair if we do the work.
Or call or text (813) 710-5060 · 9am–9pm · 7 days