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Want to Become a Mechanic? 5 Common Reasons Why Some Vehicles Fail Emissions Tests

Emissions tests are an important standard practice within the automotive industry, helping vehicle owners to ensure that their vehicle isn’t emitting more than a certain amount of pollutants into the atmosphere. If you’re considering a career as a mechanic, you’ll be performing emissions tests on vehicles by hooking up testing equipment to the OBD II port (the onboard diagnostic),in addition to conducting a visual inspection. Using the diagnostic information obtained from the OBD II port, you’ll be able to check different monitors to make sure that they’re working correctly, and then determine whether a vehicle passes or fails the emissions test. 

If a vehicle happens to fail an emissions test, there are a few factors that might be at play. Below, discover five common reasons a vehicle can fail an emissions test – some or all of which you may encounter during your future career as a mechanic! 

1. After Training in Automotive Industry Practices, Know to Check the O2 Sensor 

A vehicle’s O2 Sensor, or oxygen sensor, is responsible for monitoring the amount of oxygen within the exhaust gas that leaves the engine. When this sensor isn’t working properly, it will not correctly maintain the composition of the exhaust. Not only can this lead to acceleration issues, overheating, and a lack of power from the engine, it can also cause a vehicle’s emissions to become more toxic. After completing your training in the automotive industry, check to see if a vehicle’s O2 sensor is malfunctioning, as this could be the reason that a vehicle fails its emissions test.

A malfunctioning O2 sensor could lead a vehicle to fail its emissions test

2. A Vehicle May Fail an Emissions Test Due to Poor Fuel Metering

Fuel metering is an important function within a vehicle, where a vehicle monitors the use of fuel to maintain the perfect mixture of air and fuel needed for combustion. This results in a strong engine performance – but when the fuel metering device isn’t functioning properly, the engine will obtain the wrong mixture of fuel and air. When the mixture is too fuel rich, the vehicle will burn too much gasoline, resulting in a higher level of carbon monoxide in an engine’s emissions than the standard. If this occurs, a vehicle may not be able to pass the emissions test. 

3. The Air Filter Might Be Clogged

If a vehicle fails an emissions test due to an excessive count of hydrocarbons, this may mean that the air filter is clogged. The air filter is responsible for filtering the air taken in by the engine, removing any harmful contaminants. When this filter is dirty or clogged, an engine won’t obtain the right amount of air, resulting in problems with the emissions. After learning how to become a mechanic, consider changing a vehicle’s air filter to determine whether it’s the source of a failed emissions test.

When a vehicle’s air filter is clogged, its emissions system can be affected

4. The Motor Oil Hasn’t Been Changed in Awhile

Old motor oil can cause a number of problems in any vehicle, which is why it’s so important for vehicle owners to be vigilant about changing their oil regularly. In addition to causing engine damage, old motor oil also contains a higher amount of hydrocarbons due to the fact that more contaminants have built up in the oil. These hydrocarbons will be present in a vehicle’s emissions, leading to a failed emissions test. In order to avoid this problem, ensure that drivers have their oil changed before an emissions test if they’re due for a change.

5. The Spark Plugs Aren’t Working Properly

Spark plugs provide the igniting spark that an engine relies on to combust and power a vehicle. When spark plugs are old or worn down, this may cause them to fire in the wrong order. When spark plugs don’t fire in the correct order, this can lead to problems for the emissions system, as an engine will misfire and create additional contaminants. During your automotive career, check the status of the spark plugs to see whether they could be causing a vehicle to be emitting more pollutants than normal.

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Categories: ATC News, Surrey
Tags: auto tech technician training in Vancouver, how to become a mechanic, training in automotive industry

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