Check Engine Light: Urgent or Not?

The check engine light coming on always causes a little stress. At the shop, we regularly get panicked calls: "My engine light is on, can I still drive?"

The answer: it depends. At the shop, we'll give you the keys to tell the difference between an emergency and a minor issue.

Steady vs Flashing: The Critical Difference

Steady orange light: the engine detected an anomaly, but it's generally not an immediate emergency. You can drive carefully and book an appointment soon.

Flashing orange light: more serious. Often indicates a combustion problem (misfires) that can damage the catalytic converter. Reduce speed and get it checked ASAP.

Red light: pull over safely and do not drive. Get towed.

Most Common Causes

• Loose gas cap: yes, sometimes it's that simple. Check first.
• Faulty oxygen sensor: affects consumption and emissions.
• Catalytic converter: costlier repair, often caused by an untreated issue.
• Ignition coils / spark plugs: engine misfires, power loss.
• Mass airflow sensor (MAF): poor air-fuel mixture.

What to Do When the Light Comes On

1. Check your gas cap.
2. Observe vehicle behavior: power loss, noise, smoke?
3. If the light is steady and the vehicle drives normally, book this week.
4. If the light is flashing or the vehicle acts abnormally, get checked immediately.

OBD Diagnostic

The check engine light is linked to an error code stored in the vehicle's computer. With an OBD-II reader, we can quickly identify the cause. This diagnostic takes about 15 to 30 minutes.

But note: the code indicates the symptom, not always the exact cause. An experienced mechanic interprets the code in context.

Key Takeaways

• Steady light = book soon. Flashing light = act fast.
• A loose gas cap is the silliest (and most common) cause.
• An OBD-II diagnostic quickly identifies the problem.
• Ignoring the light can turn a small issue into a major repair.
• Don't panic, but don't ignore it either.

Frequently Asked Questions

Can the light turn off by itself?

Yes, sometimes. If the issue was temporary (e.g., loose cap), the light may turn off after a few driving cycles.

How much does a check engine diagnostic cost?

Generally $50 to $100 for code reading and initial diagnosis.

Can I pass inspection with the light on?

No. A check engine light is a fail at inspection.

Does disconnecting the battery clear the light?

Yes, temporarily. But if the problem still exists, the light will return. And you'll lose diagnostic data.

Is the check engine related to brakes?

Rarely. Brakes have their own lights (ABS, brake). Check engine concerns the engine and emissions.

Garage Path57 · 7971 15e Avenue, Montréal (QC) H1Z 3N5 · (514) 433-7479