Environmental and Work Ethics
This domain tests what a vehicle emits and how emissions are controlled, and the professional conduct expected of a technician towards customers, colleagues and the environment.
Emissions and control
Petrol exhaust contains CO, HC, NOx and CO2; diesel adds particulate matter and smoke. A rich mixture raises CO and HC; high combustion temperature raises NOx. Controls: the three-way catalytic converter (platinum, palladium, rhodium) works in closed loop near the stoichiometric mixture; EGR lowers peak temperature and so NOx; PCV and EVAP keep crankcase and fuel vapours out of the atmosphere; the diesel particulate filter traps soot; SCR injects AdBlue (aqueous urea) into the exhaust to cut NOx. Bharat Stage VI norms, in force in India since April 2020, correspond broadly to Euro 6.
Waste and ethics
Used oil goes to a registered recycler, never down a drain; lead-acid batteries are returned under the battery waste rules; tyres and used filters are segregated; refrigerants are recovered, not vented. Ethics: honest diagnosis and billing, no unnecessary parts, confidentiality about the customer's vehicle, punctuality, careful handling of the car, recording defects found, and refusing to bypass emission controls.
Worked example
A car fails its PUC test on CO, and the technician finds a thermostat stuck open so the engine runs cold. Reasoning: a cold engine needs a rich mixture, so CO and HC rise, and the catalyst is below light-off temperature. Fix the cooling fault and re-test before touching the catalyst, because a converter cannot clean a rich mixture indefinitely.
Traps
Thinking a catalytic converter reduces CO2; pouring AdBlue into the fuel tank; mixing used oil with solvent; removing a thermostat to cure overheating; promising a repair without a diagnosis.