Emissions have become quite an important point with the rising awareness for pollution control. World leaders are giving great significance to controlling pollution. In India too, we have the Pollution Under Control (PUC) certificate that every car needs, to ply on the road. Without this PUC certificate, you can endure a steep fine depending on the state. In today’s article, we will see reasons your car might fail the PUC test. 

Rich fuel mixture

Reasons for failed PUC test

If you see high emissions of CO2 in your PUC test, they are caused by high carbon monoxide levels by rich fuel to air mixture in the cylinders. It is better to check the O2 sensor for malfunctioning. Other things you can check are the injectors for leaks and worn-out fuel pumps.

Defective Ignition System

Reasons for failed PUC test

A defective ignition system causes high hydrocarbon emissions leading to a failed PUC test. This happens mostly due to poor maintenance or less running of the car. Things you need to check or replace include spark plugs and over-advanced ignition timing. You can also clean the fuel injectors to rectify this problem.

Reasons for failed PUC test – Damaged catalytic converter

Reasons for failed PUC test

The catalytic converter is one of the most important components that controls emissions. It is responsible for converting toxic gases into cleaner tail-pipe emissions. Inspect the catalytic converter for any damage before an emission test, as this is one of the most common reasons for a failed PUC test. 

Faulty Air Injection System

The air system injects fresh air into the exhaust to control the levels of hydrocarbons and carbon monoxide emissions. A faulty air injector system leads to a higher level of hydrocarbons and carbon monoxide, leading to a failed PUC test. 

Reasons for failed PUC test – Faulty oxygen sensors

Reasons for failed PUC test

The oxygen or O2 sensor is designed to measure the amount of oxygen in the exhaust gas. Its malfunction can lead to a leak in the exhaust, allowing harmful fumes to pass through the catalytic converter, resulting in a failed PUC test. A failed O2 sensor is also bad for the car as it leads to overheating and loss of power from the engine.

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