Performing proper and regular vehicle maintenance according to your owner manuals and not tampering with the emission control equipment are keys to passing smog check.
Drive your car for about 20 minutes before arriving at your smog inspection center. This will give your car enough time for proper engine combustion to occur.
Check your tires and tire pressure. Uneven, worn tires and incorrect tire pressure may cause incorrect emission test results.
Emission levels can be lowered by using fuel additives to the gas tank, which improves your combustion process and engine performance.
Regular oil changes can help you pass your smog check. Bad fumes from your oil pan leak into your engine and can fail your smog inspection.