Wondering what could be the possible reasons your car might fail the pollution test? While there may be many factors regarding the same, one of the most common problems is that the vehicle has been in use for long durations to warm up the catalytic converter for it to begin controlling the vehicle’s emissions. However, if the vehicle still fails the emission test, then below discussed are a few reasons that can be the cause. 

6 Reasons Your Car Might Fail the Pollution Test

1. Damaged Catalytic Converter

The emissions of your vehicle are controlled by many components in the vehicle but, the most important one is the catalytic converter. Make sure that you inspect the catalytic converter for any sort of damage before an emission test. This is required as the catalytic converter is responsible for converting toxic gases into cleaner tail-pipe emissions. If you find that the catalytic converter is damaged or is not functioning properly, then your car is certainly going to fail the pollution test.

2. Faulty Oxygen Sensor

The oxygen sensor is responsible for measuring the amount of oxygen in the exhaust gas. Also, O2 sensor malfunction is not uncommon, the readings of the O2 sensor could also be thrown off if there is any sort of leak in the exhaust that could allow harmful fumes to pass through the catalytic converter thereby resulting in a failed emission test. Besides this, a faulty O2 sensor can also lead to overheating, higher toxic emissions and loss of power from the engine.

3. Defective Ignition System

Next comes the faulty ignition system. This happens mostly in situations when the vehicle has not been maintained properly or has not been in operation for a long time. The things that you need to check include worn-out spark plugs, defective spark plug wires, over advanced ignition timing, or your fuel injectors that need to be cleaned.

4. Rich Fuel Mixture

If you notice that your vehicle is emitting high levels of CO2, this is usually caused by high carbon monoxide levels that could be due to an ignition system, or a rich fuel to air mixture in the cylinders of the engine. If this is the reason for your vehicle failing an emission test, it is worth inspecting the O2 sensor for malfunctioning, the injectors for leaks, or a worn-out fuel pump.

5. Vacuum System Leak

Next, comes the vacuum system leak or wear out in a vehicle. A leak in the system emits a distinct smell, thus helping you rectify before the fault begins affecting other components of the vehicle.

6. Faulty Air Injection System

The job of the air-injection system is to help bring down the hydrocarbons and carbon monoxide emissions of a vehicle. Also, if the system develops a fault, your vehicle would be emitting higher levels of carbon monoxide and hydrocarbons.

The above discussed are some of the top reasons for your car might fail the pollution test. Make sure that you inspect for the same well in time. 

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