How Emissions Testing Works, What Can Cause Failed Emission Tests and How to Avoid a Failed Test

There are many faults that can lead to failed emissions tests – oxygen sensors, mufflers, the catalytic converter, the pipes in your car’s exhaust system can all be the culprits. Emissions tests are specific protocols developed to check whether vehicle engines function in compliance with technical standards – if your vehicle fails the test, you might not be able to renew your vehicle’s registration, so here are a few details about how the testing goes and what can cause your vehicle to fail the test.

How the Testing Goes

Motor vehicles are among the most significant contributors to air pollution and auto makers are required to meet increasingly stringent conditions regarding the levels of noxious gases emitted by the vehicles they manufacture. All vehicles on the road must meet emissions-related requirements and their compliance with these requirements is verified by means of the emissions test.

During the testing procedure, the vehicle is taken to a garage authorized to perform testing. The vehicle is then tested with the help of OBD (on-board diagnostic) testers and other devices to determine emissions levels.

Causes of Failed Emissions Tests

There are many components in your vehicle’s engine and exhaust system that might lead to a failed emissions test:

  • Oxygen sensors – these parts measure the quantity of oxygen in the car’s exhaust gas and orders the vehicle’s computer to adjust functioning based on its findings. The fault of the sensor will lead to functioning errors and the exhaust gases will exceed allowed parameters,
  • Catalytic converters Denver guidelines – these units are responsible for removing impurities from the exhaust gases. If they break down or become clogged, the fault affects fuel mileage as well as the composition of the exhaust gases in a negative way,
  • Mufflers – if your mufflers are bent, rusty or have holes, the fault may cause gas leaks and lead to failing the emissions test.

How to Remedy the Problem

To be able to solve the problem, you need to know exactly what has caused it. OBD testers can be used not only to determine the composition of the exhaust gases, but also for identifying the faulty part. In many cases, faulty parts can be repaired – mufflers can be welded and catalytic converters can be cleaned, but you need a mechanic specializing in this type of work to determine whether repair or replacement is the best course of action. Repairs are usually cheaper, but they might take longer to carry out then replacements. If the faulty part cannot be repaired, you can choose to have a new part ordered for your car, but in many cases reconditioned parts are just as good, while also being way cheaper. If the fault was caused by the catalytic converter, you have two choices again: you can choose car-specific or you can buy universal converters, either solution having its own benefits. Once the repaired or new part is mounted in your car, it is a good idea to put the car on the tester again prior to the official testing to make sure everything is in good order.