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Enes, Volvo Technician
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what is Diesel emission control systems and can i hlep me

Customer Question

what is Diesel emission control systems
and can i hlep me to Research:
1. National Environment Protection Measure for Diesel Vehicles (Guidelines)
• Give a brief explanation of what this involves.
Submitted: 5 years ago.
Category: Car
Expert:  Enes replied 5 years ago.

Hello and welcome to my name isXXXXX'm a Certified Volvo Car Expert Mechanic.I'm going to try to help you find the help you need.


what info do you need im not sure what you need to know ?




catalyst consists of a stainless steel canister that contains a honeycomb structure called a substrate or catalyst support. There are no moving parts, just large amounts of interior surface area. The interior surfaces are coated with catalytic metals such as platinum or palladium. It is called an oxidation catalyst because the device converts exhaust gas pollutants into harmless gases by means of chemical oxidation. In the case of diesel exhaust, the catalyst oxidizes CO, HCs, and the liquid hydrocarbons adsorbed on carbon particles. In the field of mobile source emission control, liquid hydrocarbons adsorbed on the carbon particles in engine exhaust are referred to as the soluble organic fraction (SOF) -- the soluble part of the particulate matter in the exhaust. Diesel oxidation catalysts are efficient at converting the soluble organic fraction of diesel particulate matter into carbon dioxide and water.

Customer: replied 5 years ago.

this is my project so i need pick one of the car to be my topic .so i choose 2008 nissa tiida so can u tell me . National Environment (AUS)Protection Measure for Diesel Vehicles (Guidelines)
• Give a brief explanation of what this involves.



Expert:  Enes replied 5 years ago.
You need to know what the and how the system works on cotrolled in car is that what you need ?
Customer: replied 5 years ago.
Expert:  Enes replied 5 years ago.

How the Oxygen Sensor Fights Pollution

Originally called a "Lambda Sensor" when it was first used in fuel-injected European cars, the oxygen sensor monitors the level of oxygen (O2) in the exhaust so an onboard computer can regulate the air/fuel mixture to reduce emissions. The sensor is mounted in the exhaust manifold downpipe(s) before the catalytic converter or between the exhaust manifold(s) and the catalytic converter(s). It generates a voltage signal proportional to the amount of oxygen in the exhaust.

The sensing element on nearly all oxygen sensors in use is a zirconium ceramic bulb coated on both sides with a thin layer of platinum. The outside of the bulb is exposed to the hot exhaust gases, while the inside of the bulb is vented internally through the sensor body or wiring to the outside atmosphere.

When the air/fuel mixture is rich and there is little O2 in the exhaust, the difference in oxygen levels across the sensing element generates a voltage through the sensor's platinum electrodes: typically 0.8 to 0.9 volts. When the air/fuel mixture is lean and there is more oxygen in the exhaust, the sensor's voltage output drops to 0.1 to 0.3 volts. When the air/fuel mixture is perfectly balanced and combustion is cleanest, the sensor's output voltage is around 0.45 volts.

The oxygen sensor's voltage signal is monitored by the onboard engine management computer to regulate the fuel mixture. When the computer sees a rich signal (high voltage) from the oxygen sensor, it commands the fuel mixture to go lean. When it receives a lean signal (low voltage) from the oxygen sensor, it commands the fuel mixture to go rich. Cycling back and forth from rich to lean averages out the overall air/fuel mixture to minimize emissions and to help the catalytic converter operate at peak efficiency, which is necessary to reduce hydrocarbon (HC), carbon monoxide (CO) and oxides of nitrogen (NOX) levels even further.

The speed with which the oxygen sensor reacts to oxygen changes in the exhaust is very important for accurate fuel control, peak fuel economy and low emissions. The air/fuel mixture in an older carbureted engine doesn't change as quickly as that in a throttle body fuel-injected vehicle, so response time is less critical. But, in new engines with multipoint fuel injection, the air/fuel mixture can change extremely fast, requiring a very quick response from the oxygen sensor.


catalytic converter, there are two different types of catalyst at work, a reduction catalyst and an oxidation catalyst. Both types consist of a ceramic structure coated with a metal catalyst, usually platinum, rhodium and/or palladium. The idea is to create a structure that exposes the maximum surface area of catalyst to the exhaust stream, while also minimizing the amount of catalyst required, as the materials are extremely expensive. Some of the newest converters have even started to use gold mixed with the more traditional catalysts. Gold is cheaper than the other materials and could increase oxidation­, the chemical reaction that reduces pollutants



catalytic converter is a device that uses a catalyst to convert three harmful compounds in car exhaust into harmless compounds.

The three harmful compounds are:

  • Hydrocarbons (in the form of unburned gasoline)
  • Carbon monoxide (formed by the combustion of gasoline)
  • Nitrogen oxides (created when the heat in the engine forces nitrogen in the air to combine with oxygen)

Carbon monoxide is a poison for any air-breathing animal. Nitrogen oxides lead to smog and acid rain, and hydrocarbons produce smog.

In a catalytic converter, the catalyst (in the form of platinum and palladium) is coated onto a ceramic honeycomb or ceramic beads that are housed in a muffler-like package attached to the exhaust pipe. The catalyst helps to convert carbon monoxide into carbon dioxide. It converts the hydrocarbons into carbon dioxide and water. It also converts the nitrogen oxides back into nitrogen and oxygen.

Enes and 9 other Car Specialists are ready to help you
Customer: replied 5 years ago.
yeah by the way did you have some website link for those answer?~
Expert:  Enes replied 5 years ago.
there lot web sites you like web links to some web pages you need web page to have link how oxygen sensor works and how cataltyic converter works to reduce emission ?
Customer: replied 5 years ago.

okay thats great .cheers

Expert:  Enes replied 5 years ago.
i let you know i have to find it
Customer: replied 5 years ago.
Customer: replied 5 years ago.

thx but do u know why is the

Catalytic Converter emission control system. if u know can u locate that part for if u have photo will be good idea?~

Expert:  Enes replied 5 years ago.
That is all I have
Customer: replied 5 years ago.

thx so can you hlep me answer 5 more question i will add bouns for you!

which emission(s) the system controls


  • how the emissions are formed

  • how theirements emission(s) are controlled
  • Explain how the system/components are tested
  • Describe the symptoms resulting from faulty system components (what will the customer complain about?)
  • Describe any servicing requ
Expert:  Enes replied 5 years ago.

here is the info



how the emissions are formed:


Car emissions are biproducts of the internal combustion engine of a car, which is released into the atmosphere via the car's exhaust system. These emissions are significant contributors to air pollution and also form the main ingredients required to create smog in many of the larger cities around the world. In this respect, emissions are of importance as they have been found to have many detrimental effects on both public health and the environment.

Hydrocarbons are toxins which form the main ingredient in smog (see also ‘Smog' section). They are formed when fuel is burned in the car and are can be described as burned or partially burned fuel

Carbon Monoxide (CO) is an odourless, colourless and tasteless gas which is highly toxic to humans. It is responsible for the majority of fatal air poisoning incidents in developed countries, In cars, carbon monoxide is produced as a result of incomplete combustion of the fuel.

Mono-nitrogen oxides can be either nitrogen oxide (NO) or nitrogen dioxide (NO2). Consequently, they are often generically referred to as "NOx" pollutants (effectively,


NOx is a mixture of NO and NO2).
They are generated when nitrogen in the air reacts with oxygen under the conditions of high temperature and pressure in the engine. NOx is a precursor to smog and acid rain. NO and NO2 react with water, ammonia and a number of other compounds to form (amongst other nasties), nitric acid vapour.
Nitric acid vapour can penetrate deep into lung tissue and damage it


Generally the emission of Carbon dioxide from a car is considered a "best case scenario" (it means that fuel is being burned effectively), it is still a greenhouse gas.

Motor vehicle Carbon Dioxide emissions form a significant part of the man made contribution to the growth of Carbon dioxide concentrations in the atmosphere which is believed by a majority of scientists to play a significant part in climate change

A photochemical smog is the chemical reaction of sunlight, nitrogen oxides (NOx) and volatile organic compounds (VOCs) in the atmosphere, which leaves airborne particles (called particulate matter) and ground-level ozone.

Nitrogen oxides are released by nitrogen and oxygen in the air reacting together under high temperature and pressure of the car engine (as well as industrial manufacturing factories). VOCs are released from man-made sources such as gasoline (petrol) as well as paint, solvents and pesticides




how theirements emission(s) are controlled:


The need to control car emissions, such as hydrocarbons, NOx and carbon monoxide, has lead to the development of a number of pollution control devices in the car. The desire to reduce emissions has also, over the course of time, necessitated the computerisation of the car.

In 1981, the first of a series of advancements as a "self adjusting engine" which featured a feedback control system. This consisted of an oxygen sensor fitted on the exhaust system, which would measure the oxygen content of the emissions. It would then send a signal back to a computer which would analyse the oxygen value and adjust the air / fuel mix accordingly.

As the onboard computer systems advanced, they were also able to adjust things like ignition spark timing and control other emission monitoring systems on the vehicle. Now, computer systems are so advanced that they are capable of self - diagnosing, alerting the driver to any outages with a warning light on the dash. At the same time, the computer logs the issue internally with other diagnostic information which can later be examined by a technician.

Generally, emissions are controlled in three ways:

1. To promote more complete combustion in the engine, so there are generally less bi products such as carbon monoxide and hydrocarbons to be emitted.

2. To reintroduce hydrocarbons back into the engine and give the a "second chance" of complete combustion and conversion into less harmful compounds
3. To provide an additional area for combustion to take place (this is how catalytic converters function).

Evaporative Controls



Explain how the system/components are tested:


The electronic emissions control unit or computer monitors
certain powertrain functions and controls various operating parameters
to help the vehicle run efficiently and with the lowest possible
emissions. Ignition, transmission function, air injection, exhaust
gas recirculation (EGR), engine operating temperature and fuel system
parameters are some of the systems monitored and/or controlled by the
electronic emissions control unit car computer .

The onboard emissions diagnostic device monitors the operation of
a vehicle's emission control system and alerts the driver with a
dashboard light when malfunctions occur. The system will record where
the problem is occurring and assist automotive technicians in
diagnosing and repairing emission control malfunctions. Since some
emission control malfunctions do not have an adverse effect on vehicle
performance, they can go undetected by the driver for quite some time.
The onboard diagnostic device will help catch malfunctions early,
preventing a significant output of harmful exhaust emissions from your
vehicle, and possibly in time to be covered by the emissions control
warranty. Often this "device" is part of the electronic control unit
mentioned above.




Exhaust Gas Conversion Systems

oxygen sensor thermal reactor
catalytic converter dual-walled exhaust pipe

Exhaust Gas Recirculation System

EGR valve thermal vacuum switch
EGR solenoid EGR spacer plate
EGR backpressure transducer Sensor and switches use to
control EGR flow

Evaporative Emission Control System

purge valve fuel filler cap
purge solenoid vapor storage canister and filter

Positive Crankcase Ventilation (PCV) System

PCV valve PCV solenoid

Air Injection System

Air pump diverter, bypass, or gulp valve
reed valve anti-backfire or deceleration valve

Early Fuel Evaporative (EFE) System

EFE valve thermal vacuum switch
heat riser valve

Fuel Metering System

electronic control module (unit) or EFI air flow meter, computer
command module or mixture control unit, deceleration controls,
electronic choke, fuel injectors, fuel injection units and fuel
altitude compensator sensor, bars or rails for EFI or TBI systems,
mixture settings on sealed fuel mixture control solenoid, diaphragm
or other systems, fuel metering components that achieve closed/other
feedback control sensors/loop operation switches and valves

Air Induction System

thermostatically controlled air cleaner, air box

Ignition Systems

electronic spark advance timing advance/retard systems,
high energy electronic ignition

Miscellaneous Parts

hoses, gaskets, brackets, clamps and other accessories used in the
above systems


These are examples of other parts of your vehicle which have a
primary purpose other than emissions control but which nevertheless
have significant effects on your vehicle's emissions. If any of these
parts fail to function or function improperly, your vehicle's
emissions may exceed federal standards. Therefore, when any of the
parts of the following systems are defective in materials or
workmanship and have failed in a way that would be likely to cause
your vehicle's emissions to exceed federal standards, they should be
repaired or replaced under the emissions warranty:


  • Describe the symptoms resulting from faulty system components (what will the customer complain about?)
  • Describe any servicing requ
  • faulty system when emisson are not controlled dash warrning light will turn on and that is sign the emission are out of control to test the part system has obd2 diagnositc


    and early 1980's manufacturers started using electronic means to control engine functions and diagnose engine problems. This was primarily to meet EPA emission standards. Through the years on-board diagnostic systems have become more sophisticated. OBD-II, a new standard introduced in the mid-'90s, provides almost complete engine control and also monitors parts of the chassis, body and accessory devices, as well as the diagnostic control network of the car.


    The service industry calls the Check Engine light on your dash an "MIL" or Malfunction Indicator Light. It shows three different types of signals. Occasional flashes show momentary malfunctions. It stays on if the problem is of a more serious nature, affecting the emissions output or safety of the vehicle. A constantly flashing MIL is a sign of a major problem which can cause serious damage if the engine is not stopped immediately. In all cases a "freeze frame" of all sensor readings at the time is recorded in the central computer of the vehicle.

    Hard failure signals caused by serious problems will cause the MIL to stay on any time the car is running until the problem is repaired and the MIL reset. Intermittent failures cause the MIL to light momentarily and they often go out before the problem is located. The freeze frame of the car's condition captured in the computer at the time of the malfunction can be very valuable in diagnosing these intermittent problems. However, in some cases if the car completes three driving cycles without a re-occurrence of the problem, the freeze frame will be erased.


    service repair after the system indicated the failed part like oxygen sensor or catalytic converter you test with scanner and read output radings and repalce parts as needed

    Expert:  Enes replied 5 years ago.

    let me know if ican help you more thank you




    thx so can you hlep me answer 5 more question i will add bouns for you!

    which emission(s) the system controls


    • how the emissions are formed

    • how theirements emission(s) are controlled
    • Explain how the system/components are tested
    • Describe the symptoms resulting from faulty system components (what will the customer complain about?)
    • Describe any servicing requ
    Enes and 9 other Car Specialists are ready to help you
    Customer: replied 5 years ago.
    thx but can u

    Choose another 2 emission control systems and repeat the requirements as for the catalytic converter.

    Expert:  Enes replied 5 years ago.
    Here is two more items

    How Do Car EGR Valves Work?
    By Carrie Perles, eHow Contributor
    How Does NOx Form?
    Oxides of nitrogen (NOx) are emissions that produce smog in the atmosphere. During combusion, the hydrocarbons in fuel combine with nitrogen and oxygen in the air. This reaction usually forms water and carbon dioxide. The nitrogen in the reaction remains unchanged. However, under very high temperatures, the biproduct nitrogen combines with the oxygen and water biproducts, and eventually with other materials in the atmosphere. These reactions form NOx.
    What Does an EGR Valve Do?
    The key to lowering the NOx emissions from a car is lowering the temperature during the combustion process. The EGR valve controls the flow of air from the exhaust to the intake manifold. Because the exhaust air is cooler than the intake air, this flow will lower the temperature during combustion. In this way, the EGR valve reduces the amount of NOx in the atmosphere.

    The Evaporative Emission Control System (EVAP) is used to prevent gasoline vapors from escaping into the atmosphere from the fuel tank and fuel system.

    The EVAP system usually requires no maintenance, but faults can turn on the Check Engine light and prevent a vehicle from passing an OBD II plug-in emissions test.

    The OBD II EVAP monitor on 1996 and newer vehicles runs diagnostic self-checks to detect fuel vapor leaks, and if it finds any (including a loose or missing gas cap), it will set a fault code and turn on the Check Engine light. However, the EVAP monitor only runs under certain operating conditions. This may create a problem for the vehicle owner if his vehicle must be given an OBD II plug-in emissions test and the monitor has not completed.

    Common problems with the EVAP system include faults with the purge valve that vents fuel vapors to the engine, leaks in vent and vacuum hoses, and loose, ill-fitting or missing gas caps. The most common fault code is P0440, which indicates a large leak (often a loose gas cap). EVAP Purge valve codes (P0443 to P0449) are also common).

    The code you don’t want to see is a P0442. This indicates the system has detected a SMALL leak, but small leaks can often be a BIG problem to find. By small, we mean a leak no larger than a pin prick! Such small leaks are virtually impossible to find visually, so a special tester called a smoke machine is usually necessary to reveal the leak. The smoke machine feeds a mineral-oil based vapor into the EVAP system under light pressure (no more than a few pounds per square inch). The smoke may also contain an ultraviolet dye to make it easier to see under UV light.

    Fixing EVAP codes can be a challenge, even for professional technicians. And if you have a P0442 small leak code, you’ll probably have to take your car to a repair shop that has a smoke machine.


    The EPA requires EVAP systems on cars because gasoline fuel vapors contain a variety of different hydrocarbons (HC). The lighter elements in gasoline evaporate easily, especially in warm weather. These include aldehydes, aromatics, olefins, and higher paraffins. These substances react with air and sunlight (called a photochemical reaction) to form smog. Aldehydes are

    often called instant smog because they can form smog without undergoing photochemical changes.

    The bad thing about fuel vapors is that fuel evaporates any time there is fuel in the tank. That means if the fuel system is unsealed or open to the atmosphere, it can pollute 24 hours a day even if the vehicle is not being driven. Uncontrolled evaporative emissions like this can account for as much as 20 percent of the pollution produced by a motor vehicle.

    The EVAP system totally eliminates fuel vapors as a source of air pollution by

    sealing off the fuel system from the atmosphere. Vent lines from the fuel tank and carburetor bowl route vapors to the EVAP storage canister, where they are trapped and stored until the engine is started. When the engine is warm and the vehicle is going down the road, the PCM then opens a purge valve allowing the vapors to be siphoned from the storage canister into the intake manifold. The fuel vapors are hen burned in the engine.

    Evaporative emission controls were first required on cars sold in California in 1970. EVAP has been used on all cars and light trucks since the early 1970s.


    Sealing the fuel tank is not as simple as it sounds. For one thing, a fuel tank must have some type of venting so air can enter to replace fuel as the fuel is sucked up the fuel pump and sent to the engine. If the tank were sealed tight, the fuel pump would soon create enough negative suction pressure inside the tank to collapse the tank. On older EVAP systems, the tank is vented by a spring-loaded valve inside the gas cap. On newer vehicles, it is vented through the EVAP canister.


    The major components of the evaporative emission control

    system include:

    Fuel tank, which has some expansion space at the top so fuel can expand on a hot day without overflowing or forcing the EVAP system to leak.
    Gas cap, which usually contains some type of pressure/vacuum relief valve for venting on older vehicles (pre-OBD II), but is sealed completely (no vents) on newer vehicles (1996 & newer). NOTE: If you are replacing a gas cap, it MUST be the same type as the original (vented or nonvented).
    Liquid-Vapor Separator, located on top of the fuel tank or part of the expansion oerflow tank. This device prevents liquid gasoline from entering the vent line to the EVAP canister. You do not want liquid gasoline going directly to the EVAP canister because it would quickly overload the canister's ability to store fuel vapors. The liquid-vapor separator is relatively trouble-free. The only problems that can develop are if the liquid return becomes plugged with debris such as rust or scale from inside the fuel tank; if the main vent line becomes blocked or crimped; or if a vent line develops an external leak due to rust, corrosion, or metal fatigue from vibration.

    Some liquid-vapor separators use a slightly different approach to keeping liquid fuel out of the canister vent line. A float and needle assembly is mounted inside the separator. If liquid enters the unit, the float rises and seats the needle valve to close the tank vent.

    Another approach sometimes used is a foam-filled dome in the top of the fuel tank. Vapor will pass through the foam but liquid will cling to the foam and drip.

    If a blockage occurs in the liquid-vapor separator or in the vent line between it and the EVAP canister, the fuel tank will not be able to breathe properly. Symptoms include fuel starvation or a collapsed fuel tank on vehicles with solid-type gas caps. If you notice a whoosh of pressure in or out of the tank when the gas gap is removed, suspect poor venting. You can check tank venting by removing the gas cap and then disconnecting the gas tank vent line from the EVAP canister. If the system is free and clear, you should be able to blow through the vent line into the fuel tank. Blowing with compressed air can sometimes free a blockage. If not, you will have to inspect the vent line and possibly remove the fuel tank to diagnose the problem.
    EVAP Canister. This is a small round or rectangular plastic or steel container mounted somewhere in the vehicle. It is usually hidden from view and may be located in a corner of the engine compartment or inside a rear quarter panel. The canister is filled with about a pound or two of activated charcoal. The charcoal acts like a sponge and absorbs and stores fuel vapors. The vapors are stored in the canister until the engine is started, is warm and is being driven. The PCM then opens the canister purge valve, which allows intake vacuum to siphon the fuel vapors into the engine. The charcoal canister is connected to the fuel tank via the tank vent line. Under normal circumstances, the EVAP canister causes few problems. Since the charcoal does not wear out, it should last the life of the vehicle.

    The most common problem with the EVAP canister is a faulty purge control or vent solenoid. Vacuum-type purge valves can be tested by applying vacuum directly to the purge valve with a hand-held vacuum pump. The valve should open and not leak vacuum if it is good. With solenoid-type purge valves, voltage can applied directly to the solenoid to see if the valve opens. The resistance of the solenoid can also be checked with an ohmmeter to see if it is open or shorted.
    The purge control strategy on many late model EVAP systems can get rather complicated, so the best advice here is to look up the EVAP diagnostic procedures in the OEM service literature or on Alldata.


    On 1996 and newer vehicles, the OBD2 system monitors the fuel system for fuel vapor leaks to make sure no hydrocarbons are escaping into the atmosphere. The EVAP monitor does two things: it verifies there is airflow from the EVAP canister to the engine, and that there are no leaks in the fuel tank, EVAP canister or fuel system vapor lines.

    The OBD2 EVAP monitor runs once per drive cycle and only when the fuel tank is 15 to 85% full. The EVAP monitor uses a "purge flow sensor" to detect leaks as small as .040 inches in diameter on 1996-99 models, and as small as .020 inches on most 2000 and newer vehicles.


    If the OBD EVAP monitor detects a leak when it runs the EVAP leak check, it will set a fault code in the P0440 to P0457 range:
    Customer: replied 5 years ago.
    but how about the
    • State which emission(s) the system controls

    Expert:  Enes replied 5 years ago.
    Customer: replied 5 years ago.
    nope i mean you already put the answer on the chat?~ if u have can you show me once agn?~
    Expert:  Enes replied 5 years ago.
    Customer: replied 5 years ago.
    thx i jst want to know the question is
  • State which emission(s) the system controls
  • Expert:  Enes replied 5 years ago.
    State like country in USA colifornia controls many standards that apply works wide if you can meet california state standard most country accept.
    Customer: replied 5 years ago.
    okay thats great
    Expert:  Enes replied 5 years ago.
    Thank you