Why is my engine light on?

The check-engine light means the car's computer has logged a fault — anything from a loose fuel cap to a misfire or a failing sensor. The only way to know is a diagnostic scan that reads the stored code. A flashing light means stop driving — that's a serious misfire that can damage the catalytic converter.

The most common causes

1
Oxygen (O2) sensor

A common trigger — affects fuel mixture and economy.

2
Loose or faulty fuel cap

Surprisingly common and cheap — a loose cap trips the light.

Often cheap
3
Catalytic converter

A failing cat is a bigger-ticket cause the scan will confirm.

4
Misfire / ignition coils

A misfire from coils or plugs often pairs with a flashing light.

Flashing = stop
5
Mass airflow sensor or EGR

Airflow-sensor or EGR faults are also frequent culprits.

Is it safe to drive? A steady light — drive gently and get it scanned soon. A flashing light — pull over and call us; that's a serious misfire.

What it costs in Sydney

Mobile diagnostic + quote$129

The $129 is credited toward the repair if you book it with us.

Get it diagnosed — in your driveway.

We read the stored code, confirm the real fault, and give you a fixed price to fix it.

$129
Credited if you book the repair · Hills & Western Sydney
Call 0414 623 806
V

Reviewed by a Vertex mechanic — 20+ years' experience. ★ 4.9 on Google · Fixed price, every fault photographed, 12-month warranty.

Common questions

A steady light — drive gently and get it scanned soon. A flashing light means stop: that's a serious misfire that can damage the catalytic converter.

Sometimes (a loose fuel cap), but usually not. A scan tells you for certain what's wrong rather than hoping.

$129, and it's credited toward the repair if you book it with us.

Not sure exactly what's wrong?

Use our free 60-second Fault Finder — get the likely cause, whether it's safe to drive, and a fair price.

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Get the price before you book.

Any car. Anywhere. Any time — across the Hills & Western Sydney.

Call 0414 623 806