What is the Emission and Exhaust System?

A vehicle's exhaust system has four main functions:

  • Noise control
  • Control and carry away emission gases
  • Improve engine performance
  • Improve fuel consumption 

The emission system keeps the engine running cleanly and efficiently under all operating conditions. It controls and reduces the emissions, harmful exhaust gases through piping that guides reaction exhaust gases away from a controlled combustion inside an engine. It also prevents fuel vapour from escaping from the fuel tank causing problems. This is done through several sensors, computerized engine controls, and exhaust components. the system can also be linked- or includes a turbocharger to increase engine power. and a catalytic converter to reduce air pollution.

The main parts of an exhaust system are:

  • The exhaust manifold attaches to the cylinder head and takes each cylinder's exhaust and combines it into one pipe. The manifold can be made of steel, aluminum, stainless steel, or more commonly cast iron.
  • The Oxygen manifold: All modern fuel injected cars utilize an oxygen sensor to measure how much oxygen is present in the exhaust. From this the computer can add or subtract fuel to obtain the correct mixture for maximum fuel economy. The oxygen sensor is mounted in the exhaust manifold or close to it in the exhaust pipe.
  • Catalytic Converter: Converts harmful carbon monoxide and hydrocarbons to water vapor and carbon dioxide. Some converters also reduce harmful nitrogen oxides. The converter is mounted between the exhaust manifold and the muffler.
  • The muffler serves to quiet the exhaust down to acceptable levels as the combustion process is a series of explosions that create a lot of noise. Most mufflers use baffles to bounce the exhaust around dissipating the energy and quieting the noise. Some mufflers also use fiberglass packing which absorbs the sound energy as the gases flow through.
  • The Exhaust pipe carries the gas. Exhaust tubing is usually made of steel or stainless steel. Aluminized steel has better corrosion resistance than plain steel but not better than stainless steel. It is however cheaper than stainless steel.

Factors including the effectiveness of the emission system include:

  • corrosion
  • rust
  • driving conditions
  • vehicle age
  • type of spark plug electrode material
  • quality of vehicle maintenance
  • fuel quality
  • state of the vacuum hoses
  • damaged or worn sensors

Symptoms indicating possible problems with the Emission system includes:

  • Excessive smoke and vapours
  • Noise from the exhaust system
  • A flashing warning light on the dashboard


It is technically possible to drive a vehicle with a broken exhaust system but it is neither safe nor legal. It is an important part of your vehicle's propulsion system which should be attended to asap when one or more of the above symptoms are being detected. Find professional help 24/7 in the Auto Repair Directory!

Posted on May 21, 2020 by Auto Repair Directory

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