What Does a “Service Engine Soon” Light Mean?

Regular preventive maintenance helps to minimize the likelihood of the dreaded check engine light. That doesn't mean you will never see it, but it not only lessens the chance of it happening, it also reduces the chances that it will be something significant. That light isn't a warning you want to ignore even if it's inconvenient or doesn't seem urgent. It could be a myriad of problems, from something as small as you forgot to tighten your gas cap to severe engine problems.
When it's a steady light, that is usually an indication that it's a less severe problem. When it's blinking, it's a sign that it requires immediate attention no matter how full your schedule is for the day. When the check engine light is on, the problem with continuing to drive is that if it is something more serious, driving it could lead to catastrophic failure, which means there will be no fixing the problem.
In 2019, CarMD published a report of the top 10 causes of a check engine light:
- Replace catalytic converter with new OE catalytic converter
- Replace oxygen sensor
- Replace ignition coils and spark plugs
- Tighten or replace the gas cap
- Replace mass airflow (MAF) sensor
- Replace ignition coils
- Replace evaporative emissions (EVAP) purge control valve
- Replace fuel injectors
- Replace evaporative emissions (EVAP) purge solenoid
- Replace thermostat