Failing emission tests can be quite perturbing, unnerving, and frustrating. Did you have a failed emission inspection and wonder, ‘why the emission failure?’
A failed emission may make you feel like the inspectors are trying tricks on you, especially when your baby ride is running smoothly. But how do you know what’s wrong with your vehicle?
This article has provided sufficient information on the reasons for a failed emission test and how to fix it. Grab a seat; let’s reveal them.
Why A Vehicle Fails An Emission Inspection
Several factors could cause emission failures. While some are easy to fix, others are complex jobs that require expensive fixes.
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Old Motor Oil: If you are fond of not changing your engine oil at regular intervals, it’ll not only make you fail emissions, but it will also form engine sludge, which will damage the engine over time. Smog technicians measure hydrocarbons during emission inspections, and a dirty, delayed oil change can accumulate hydrocarbons.
Bad Catalytic Converter: A vehicle with a bad catalytic converter may overheat and emit a sulfuric smell. On its top, you may also perceive an odd smell like that of a rotten egg.
Why would a failed catalytic converter cause you to fail the emission test? It’s simple! Because it can convert carbon dioxide.
Bad Fuel Injectors: A failed or clogged fuel injector will disrupt the fuel passage in the injector lines. It can cause the air/fuel mixture ratio to be too lean or too rich.
If too much unburned fuel remains during normal combustion, it can result in carbon dioxide in the exhaust system, which then becomes emissions and leaves the tailpipe.
Leaking or loose gas cap: This is common, right? It occurs more often than you can imagine. As common as it is, it can cause a failed emission inspection in Cairfax. Hence, it is important to ensure the gas cap is tightened properly after refilling fuel at a gas station.
Some vehicles will give an audible click when the cap is locked.
Faulty air intake levels: If your car failed an emissions test and showed elevated hydrocarbon and carbon monoxide levels, you may have a clogged air intake system.
This is mainly due to a clogged or dirty air filter, which results in a lean air/fuel mixture. This literally means unburnt fuel escaping into the exhaust system, causing the tailpipe to emit greenhouse gases.
Lousy Oxygen Sensor: The 02 sensor works in harmony with your car’s onboard computer by regulating the oxygen levels in the exhaust system. If this car sensor fails, it’ll send false readings to the car computer, resulting in an inappropriate air/fuel mixture in the cylinders. This will trigger limp mode and lead to loss of engine power.
Now, how do a failed emission test, MOT, and lousy 02 sensors relate? When this sensor fails, the PCM will not know if the engine is operating under normal tolerances. And it will cause the vehicle to fail an emission test.
Check engine light: A check engine light on the instrument cluster, whether due to the outlined causes or other engine issues, will automatically cause your little boy to fail an emission test.
While it is quite easy to clear the check engine light on your dashboard, it is not an escape route to pass emission tests. Instead, it’ll cause a failed emission inspection, not ready.
This means it will put the vehicle in a not-ready state until system sensors start sending and receiving appropriate data from normal driving.
Once the appropriate data is recorded, the system problem that triggered the check light initially will be captured, and the light will most likely reappear.
How Do I Fix My Emission Failures
If your car has failed an emission test or you are concerned about fixing an emission failure, stay tuned. In the next few paragraphs, we will explain how to fix failures on emissions tests.
Check wheel tires: Some things to check include safety tests. Check things like tires to make sure they are not punctured and have good tread life.
Fix the headlamps and put them back into good working order. Anybody can check the light – you don’t need a mechanic to check it.
Change engine oil: Since you can’t tell what’s coming out of the tailpipe, take a few preventive measures to ensure it passes the emissions test.
In older cars manufactured before 1996, the air exiting the exhaust tailpipe is measured with a dynamometer. So, you need to put everything in good working order to ensure the air coming out of the tailpipe is very low in pollutants.
That said, make sure the oil is clean. Change the engine oil and oil filter before the inspection, because if the oil gets dirty, the PCV valve will suck dirty vapors, burn them, and pollute more.
Clean/replace the air filter: Keep it clean; a dirty one can block airflow, causing the car to run lean and pollute too much.
Check the Spark Plugs: Ensure they are in good shape. Spark plugs have a gap between the electrodes and the body. If the gap is too wide, they won’t ignite as they normally would.
Even if the car is running okay, if the gap is too much, it’ll pollute more and fail the test.
Check the cooling system: A low coolant level will make the engine run hotter and, of course, result in overheating. So make sure there’s enough coolant and that the engine isn’t overheating.
Put the cooling fan into a nice, smooth-running state. Start the vehicle and turn on the AC to check whether the fan runs smoothly. Because the test takes place on a dynamometer, the car isn’t moving; if the cooling fans aren’t running properly, the engine will run harder, and your car will fail the test.
A dynamometer is a measuring device used for determining torque or power.
For Instance, it is used to calculate the power generated by a motor, engine, or other rotating prime movers by simultaneously measuring force (torque) and rotational speed (rpm).
Older vehicles that were produced before 1996 are not equipped with an OBD11 plug-in socket. For this reason, CERTs do not test the engine with any computer other than a dynamometer
Fix engine check light: If your car was manufactured from 1996 onwards, the test will not be performed on a dynamometer. They will plug a computer into the car to see if there’s a problem.
So, if the car’s check engine light is illuminated on the dashboard, get a certified mechanic to diagnose and fix the fault before you go for the test. If there’s a trouble code stored in the computer, the scan tool will detect it.
There are over 2,000 separate fault codes that can exist in a car. This makes it difficult to determine the cause of the illuminated light without a scan tool.
Use fuel injector cleaner: If you have tried everything mentioned above and the car still fails an emission test, you can try a fuel injector cleaner and pour it into the gas tank.
I recommend using a shop-line solvent. Pour a gallon of the solvent into a half-gallon tank and drive the car on the highway at maximum speed. Drive for about 30-45 minutes.
I have done this on several cars and have gotten them to pass emissions tests. Of course, this is not magic; if your car has faults, you need to fix them. But if the car runs okay, this will help it pass the test because the solvent burns cleanly and pushes out cleaner smoke. If you have older cars with catalytic converter issues, this will help them pass the test.
FAQs
Q: What happens if I fail the emission test twice?
If your baby ride fails an emissions test, it means its emissions exceed the permissible levels for the manufacturing year.
When a vehicle fails the emission test, it is expected to be repaired and returned for another test within 60 days of the initial test.
Now, what happens if you fail an emission inspection 3 times or twice? You may qualify for a cost waiver if you meet the expenditure criteria and the repair is performed by a certified emission technician (CERT).
Q: Should I buy a car that fails the emission test?
In most parts of the United States, it’s illegal to sell a car that doesn’t pass the current emission test. If a car you intend to buy has multiple failed emission test records or doesn’t have current records for up to a year, insist the car go for an emission test or get another car.
Q: How much does it cost to fix emissions?
The cost to fix emission problems depends on the cause of the failure. However, if a faulty oxygen sensor or EVAP system is diagnosed as the culprit, the repair and diagnosis cost should be $100 to $200 per vehicle.
Q: How many miles do you have to drive to pass smog?
Remember that internal combustion engines run on fuel. Drive your car 10-15 miles before getting to the smog station. This will allow the engine to warm up and ensure that the catalytic converter, motor oil, and coolant are at normal operating temperature. It’ll also help your car pass the emissions test.
One of the emission inspection standards requires a smog technician to check that the vehicle is at normal operating temperature before running the inspection. However, this is one of the prerequisites for passing the emission inspection, and you can do it with ease.
Q: How do I get a waiver for emissions?
There are three types of emission waivers. Here’s how you can get any of them;
Cost waiver: You are expected to meet the maximum expenditure prerequisites for emission repairs. The repairs must be done by certified emission repair technicians CERT.
Economic hardship: To obtain a hardship exemption waiver, you must submit documentation to DMV stating that your annual income is below the federal and state poverty levels.
You will also attest that you have no other income or assets to pay emission repair costs.
Functional diagnosis: There must be documented reasons for the failed emission, and the documentation must be from the manufacturer, not a dealer.
The letterhead must state the reasons why the car cannot pass or is failing the emission test.
Q: What happens if I buy a car that doesn’t pass smog?
If you purchase a used car that doesn’t have a current smog test record, the dealer is required by law to fix the car so it passes smog.
Q: Can I still drive with emission problems?
As long as it is only emission problems you are experiencing at the moment, you can still drive without worrying about safety. However, you should diagnose and fix the faults before they escalate into an expensive repair.
Final word
Emission tests help ensure that only worthy vehicles are driven on the road. This is to ensure that vehicles emit less pollution into the atmosphere, protecting the environment and its inhabitants.
Having known the reasons for emission inspections, if you fail an emission test, get it fixed for the benefit of the road users.
Now, you know the reasons for a failed emission inspection and how to fix it, contact your local mechanic to fix it or drive down to CERT for a professional fix.
