Check Engine Warning Light
The Check Engine Light, or Malfunction Indicator Lamp (MIL), means the engine computer has detected a fault in the engine, emissions, fuel, ignition, or related control system.
If the light is steady, scan the vehicle and arrange diagnosis soon. If it is flashing, reduce load and stop driving as soon as it is safe because a severe misfire can damage the catalytic converter.
The Check Engine warning light is one of the most common dashboard warning lights. The ECM/PCM turns on the MIL when it detects a fault that can affect engine operation or emissions. The exact cause cannot be identified from the light alone; an OBD-II diagnostic scan is required.
⚠️ Drive With Caution
A steady Check Engine Light is usually drivable for a short distance if the vehicle runs normally. A flashing light or severe misfire requires stopping as soon as safely possible.
$20-$2,500+ depending on the confirmed fault
Repair costs vary depending on the exact diagnostic trouble code, vehicle make and model, labor rates, and which component has failed. Always diagnose the problem before replacing any parts.
The Check Engine Light identifies a detected fault, not a single failed part. Use an OBD-II scan and proper testing to find the cause instead of replacing parts based only on the warning light.
What does the Check Engine light mean?
It means the engine computer has logged a fault affecting engine operation or emissions. The light alone does not identify the part; it only tells you a diagnostic code has been stored.
Can I drive with the Check Engine light on?
A steady light with the engine running normally is usually fine for a short trip to a workshop. A flashing light signals an active misfire that can destroy the catalytic converter, so pull over as soon as it is safe.
How is a Check Engine light diagnosed?
Start with an OBD-II scan for stored and pending codes, then note whether the light is steady or flashing. Inspect the fuel cap, intake, spark plugs, coils, injectors, and oxygen sensors, and bench-test or live-test the component the code names before buying parts.
How much does it cost to fix a Check Engine light?
Anywhere from about $20 for a replacement fuel cap to $2,500 or more for a catalytic converter. Most workshops charge $90-$150 for the diagnosis itself before any repair is quoted.
See every fault code, sensor test, and repair step for P0300