All registered vehicles are subject to an annual or semi-annual safety inspection to ensure safe operation on public roads and streets. During these tests, most cars and trucks should also pass an emissions test. If the vehicle fails, you will not receive a valid inspection tag. In most cases, the problem must be repaired and the vehicle must be re-inspected within 30 days. These are the most common reasons why cars do not pass an emissions test.
1. Defective O2 Sensor
When the oxygen sensor in your car breaks down, you can not accurately measure the amount of oxygen in the exhaust gas. This can increase the toxicity of the fumes that are expelled from your exhaust, which almost always results in a failed inspection. In addition to possibly increasing the toxicity of the exhaust gases, a defective O2 sensor can reduce engine power and fuel efficiency. In extreme cases, it can also cause motor overheating. Replacing the part usually costs between two and three hundred dollars at your local garage.
2. Inadequate fuel measurement
Several automotive components work together to ensure that the proper amount of gasoline is always on. If there is a problem with the fuel injection unit, the carburetor or the engine control unit, the measurement may be adversely affected, causing more gas to burn than necessary. As expected, a vehicle that uses more gas than necessary will not pass the emission test. These problems can cost several hundred dollars to repair.
3. Rich fuel mixture
Also known as high and high amount of carbon monoxide in the exhaust of your car, your engine is burning a lot of gasoline. There are numerous explanations for a rich blend of fuel including fuel injector leakage, a faulty oxygen sensor, excessive pressure or a defective airflow sensor. Either of them will probably give you back a few hundred dollars.
A leak in your car’s exhaust system can cause all sorts of problems, from less fuel efficiency and increased engine noise to pedal vibrations and much dirtier gases. As the problem results in O2 sensor readings, even a small leak can cause a failure in the inspection. The repair costs of the problem can range from less than one hundred to several hundred dollars.
5. EVAP system malfunction
The Evaporative Emission Control System (EVAP) of your car is responsible for avoiding the emission of toxic exhaust gases into the atmosphere. If there is a leak in the hoses or vacuum vents, a defective bleed valve or even a loose or cracked gas cap, the system will not perform its main function. The repair of these problems is usually economical, since the affected components are easily accessible, but you need to hire the professionals as you’ll need the Smoke machines to detect the leak.
If you do not pass your next emissions test, there is a good chance that one of these problems is to blame.