Pollution Certificates: Bs6 Engines And Their Compliance

India is one of the most polluted countries in the world, with air pollution being the fifth-largest killer. In 2017, the Indian government imposed stricter BS6 emission norms to curb rising pollution. BS6 norms define the maximum permissible pollutant level that can be emitted by a car or two-wheeler exhaust. All vehicles running on Indian roads require a pollution certificate, and BS6 vehicles are no exception. Vehicle owners must carry a valid Pollution Under Control (PUC) Certificate and comply with the prescribed emission norms. BS6 vehicles can obtain a pollution certificate from an emission testing centre.

Does BS6 Engine Need Pollution Certificate?

BS6 vehicles and pollution certificates in India

With millions of vehicles running on Indian roads, carbon monoxide emissions are a vital contributing factor to the rising pollution in the country. In 2017, the Central Government imposed more stringent BS6 emission norms to curb this. Bharat Stage Emission Standards is the governing body that regulates the pollution output emitted by vehicles in India.

The BS6 norms are the sixth iteration of the emission norms and are a substantial leap from the BS4 norms in terms of reducing pollution. The transition from BS4 to BS6 norms for vehicles in India required vehicle manufacturers to alter several parts of the two-wheelers to comply with the norms. This included changing the calibration and combustion of the engine, improving fuel injection, and increasing cylinder pressures following NOx and PM treatment solutions.

BS6 vehicles do not emit as much pollution as older vehicles. However, they do produce some emissions, although they lie in a permitted range. As per the law, every vehicle on Indian roads requires a pollution certificate or PUC (Pollution Under Control) certificate. The procedure for procuring one is the same as that of the BS4 vehicles. It is mandatory to have a PUC certificate to know the pollution generated by the vehicle. The requirement of a pollution check certificate for BS6 vehicles comes into effect after a period of 2 years or 20,000 km.

Do BS6 engines produce emissions?

The Bharat Stage 6 (BS6) engine is an upgraded version of its predecessor, BS4, with stricter norms to curb the rising pollution in India. The BS6 engines are designed to reduce emissions and will be compliant with the new emission standards.

The new BS6 engines will have a Selective Catalytic Reduction (SCR) unit, which is an advanced emissions control unit. The SCR unit will reduce the emission of nitrogen oxide (NOx) by increasing the combustion temperature, which in turn reduces the production of particulate matter (PM) in the engine. The NOx, although it increases, is controlled by the SCR using catalytic reduction. The SCR also increases fuel efficiency and provides better power. The inclusion of SCR in the engine increases its life and reduces the maintenance period.

The BS6 engines will also have a Diesel Particulate Filter (DPF) installed in the exhaust systems to reduce the soot or particulate matter. The DPF, along with the SCR, is essential to achieve the required reduction in pollutants. The DPF is usually placed before the SCR or after the LNT (Lean NOx Trap) in the exhaust system. The DPF, however, does not respond well to sulphur, and excessive sulphur can clog the filter.

The BS6 fuels will have a lesser amount of sulphur, leading to lower emissions. The sulphur content in BS6 fuel will be 10 parts per million (ppm), compared to 50ppm in BS4 fuels. The BS6 engines will also control SOx (Sulphur Oxides) by removing the sulphur content from the diesel fuel.

The BS6 engines, although designed to reduce emissions, do produce some emissions, although they lie in a permitted range. The pollution or emissions from a BS6 car depend on the condition of the exhaust system.

Do you need a pollution certificate for a new bike?

In India, any new bike must have a valid Pollution Under Control (PUC) Certificate to be road legal. This certificate ensures that the vehicle meets the emission standards set by the government. The PUC Certificate is mandated by the Motor Vehicles Act, 1988, and driving without one can result in penalties.

The PUC Certificate is issued by authorised emission testing centres across India. The two-wheeler's exhaust gas is tested to determine its emission levels. The emission testing measures various pollutants in the exhaust, including carbon monoxide (CO), hydrocarbons (HC), carbon dioxide (CO2), smoke density, and idling CO. The result is compared with the permissible emission limits set by the government to verify that the vehicle does not exceed the allowed pollution levels.

The PUC Certificate for new two-wheelers is valid for one year from the purchase date. After that, it must be renewed every six months. The charges for getting a PUC Certificate for a bike range between ₹60 and ₹100.

Regarding BS6 vehicles, there is some discrepancy in the information I found. One source states that BS6 vehicles do not need a pollution certificate for the first two years or 20,000 km, as they emit much less pollution than older vehicles. However, another source mentions that there are no changes in the laws, and even BS6 vehicles require a pollution certificate.

SCR, DPF, and SOx control in BS6 diesel engines

In India, the introduction of BS6 norms for exhaust emissions was a significant development, especially given the rising pollution in metro cities. This shift from BS4 to BS6 was a big challenge for automotive manufacturers, who had to invest heavily in R&D to develop compliant engines.

To meet the stricter emission norms, manufacturers of diesel engines have adopted Selective Catalytic Reduction (SCR) and Diesel Particulate Filters (DPF) technologies. SCR is an advanced active emissions control technology that injects a liquid reductant agent, typically automotive-grade urea or Diesel Exhaust Fluid (DEF), into the exhaust stream of a diesel engine. This process helps to reduce harmful nitrogen oxide (NOx) emissions.

DPF, on the other hand, is an exhaust after-treatment device that traps particulate matter such as soot and ash. It usually has a ceramic substrate formed into a honeycomb structure. DPFs can become clogged with soot and ash, requiring active or passive regeneration to clean them. Active regeneration involves the engine injecting fuel into the exhaust stream, which creates heat to convert soot to carbon dioxide. Passive regeneration occurs during normal driving when the engine's heat combines soot and carbon with oxygen to create carbon dioxide, which can pass through the filter.

Both SCR and DPF technologies help to meet the BS6 emission norms. Additionally, to control SOx (sulphur oxide) emissions, sulphur content is removed from diesel fuel. These technologies and fuel adjustments ensure that BS6 diesel engines produce significantly reduced emissions compared to older vehicles.

On-Board Diagnostics (OBD) in BS6 petrol vehicles

In India, vehicles are required to have a pollution certificate to be driven on the road. The introduction of BS6 vehicles brought about a new set of emission norms, with a particular focus on reducing nitrogen oxide, soot or particulate matter, and sulphur oxide emissions.

BS6 petrol vehicles are equipped with more advanced On-Board Diagnostics (OBD) systems. OBD refers to a vehicle's self-diagnostic and reporting capability, which is used to monitor critical engine components' performance and other parameters such as speed, torque, and fuel parameters. The OBD-II connector is a direct feed into the vehicle's Electronic Control Unit (ECU), recording faults, tracking performance, and logging everything from a misfire to a failing catalytic converter. The OBD-II port connects to the ECU, pulling live data from sensors and logging Diagnostic Trouble Codes (DTCs) when something malfunctions.

The OBD system in BS6 petrol vehicles provides real-time emission updates, allowing vehicle owners or technicians to access the status of various vehicle subsystems and obtain "pending" diagnostic trouble codes detected during the current or last completed driving cycle. This information is useful for service technicians after a vehicle repair, as it helps determine if the repair has fixed the problem.

OBD-II scanners can be connected to the vehicle's OBD port, usually located under the dashboard near the steering column. These scanners provide detailed information about the vehicle's performance and can be used to diagnose problems before taking the vehicle to a repair shop. The data from the vehicle can be accessed via a smartphone application, which communicates with the OBD device via Bluetooth or Wi-Fi.

While BS6 vehicles produce significantly reduced emissions compared to older vehicles, they do still emit some pollutants. Therefore, a Pollution Under Control (PUC) certificate is required to ensure that the vehicle meets the government's emission guidelines. The requirement for a pollution check certificate for BS6 vehicles comes into effect after a period of 2 years or 20,000 km.

Frequently asked questions