Smog removal - Valencia Auto Performance & Simply Smog in Santa Clarita

Common Reasons Vehicles Fail the California Smog Inspection

Every two years in California, many people have the same concern—will I pass my smog test? Unfortunately, if you don’t pass your emissions inspection, you cannot renew your vehicle registration, which means you cannot legally drive until you pass the test. Doubly stressful, you may be worried the repairs you need to fix the issue are going to be expensive. Honestly, sometimes they are, and sometimes they’re not. (You may just need an oil change, which is maintenance you need to take care of anyway.) From simplest to more serious, here are some common reasons vehicles fail the California smog inspection.

Bad gas cap

Another simple, inexpensive fix that may help you pass your smog test—replacing your gas cap if it’s missing, loose, or cracked. A bad gas cap can cause your Evaporative Emission Control System (EVAP) to malfunction.

Leaking vacuum hose

Like with a bad gas cap, your EVAP system will not be able to function as it should if you have a leak in a connected vacuum hose. The leak will allow gasoline vapors to be released into the air, and cause you to fail your smog inspection.

Gas Tank Cap

Malfunctioning O2 sensor or mass air flow sensor

Your O2 sensor’s job is to monitor your vehicle’s exhaust fumes. A faulty O2 sensor or mass air flow sensor can cause your vehicle to burn too much gas, and increase the hazardous fumes—namely, carbon monoxide—within your car’s exhaust.

Malfunctioning fuel injection unit

When your vehicle’s computer aided fuel injection unit malfunctions or fails, the air-to-fuel ratio in the engine can become imbalanced, often causing your car to run rough and fail smog.

Internal engine leaks

One leak in your fuel pump or other part of your engine can cause your vehicle to fail an emissions test.

Not changing the oil and filter

It’s smart to get an oil change before you go for your smog test. The computers in newer cars will often throw up an error if you haven’t changed your oil and filter for thousands of miles.

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Performing regular and proper maintenance according to your vehicle’s owner’s manual will help improve your car’s chances of passing a California smog test. If your check engine light comes on, it’s best to bring your vehicle in for diagnostics and service as soon as possible. Do not wait until your car’s next scheduled smog check. You could do greater damage to your engine or emission-control systems.

For automotive maintenance, smog testing, and emissions-related repairs in the Santa Clarita Valley, come to Valencia Auto Performance & Simply Smog. You can trust us to keep your vehicle in smog check passing condition, and handle any necessary emissions repairs honestly and correctly.