Troubleshooting6 min read
10 Most Common Check Engine Light Causes and Fixes
Don't panic when your check engine light comes on. Learn the most common causes and what you can do about them.
Don't Panic – But Don't Ignore It
When your check engine light illuminates, it can trigger anxiety. However, it doesn't always mean catastrophic failure. Here are the most common causes.
1. Loose or Damaged Gas Cap
Symptoms: Light comes on after refueling Fix: Tighten or replace the gas cap Cost: $0-$25
2. Oxygen Sensor Failure
Symptoms: Decreased fuel economy Fix: Replace oxygen sensor(s) Cost: $150-$500
3. Catalytic Converter Issues
Symptoms: Reduced performance, sulfur smell Fix: Replace catalytic converter Cost: $500-$2,500
4. Mass Airflow Sensor (MAF)
Symptoms: Rough idle, stalling, poor acceleration Fix: Clean or replace MAF sensor Cost: $100-$400
5. Spark Plug/Ignition Coil Problems
Symptoms: Engine misfires, rough running Fix: Replace spark plugs and/or coils Cost: $100-$500
What to Do When the Light Comes On
- Check if it's flashing – A flashing light means severe misfire. Pull over safely.
- Check the gas cap – Tighten it and drive for a day.
- Get the code read – Auto parts stores often read codes for free.
- Don't ignore it – Even minor issues can become major problems.