1. Inspect your vehicle's air filter. A dirty air filter can restrict airflow to the engine, causing it to run rich and produce high levels of carbon monoxide. Inspecting the air filter is a quick and easy task that can be easily taken care of from most parts stores around you!
4. Check and replace spark plugs
6. Remove carbon deposits
8. Test oxygen sensor and replace if needed
10. Replace PCV (positive crankcase ventilation) valve
12. Check exhaust gas recirculation (EGR) system
