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Under Procedure
3(I) MOTOR VEHICLES (Control of Smoke And Gas Emission) Rules P.U.(A) 414/1977 under Section 57 Road Transport Act 1987 equable :

No body can use or effectuate to use a motor vehicle which smoke emission more than 50 HSU".

If found guilty, can be fined not exceeding RM500 and imprisoned no exceeding 2 weeks for the first time, can be fined not exceeding RM1,000 and imprisoned not exceeding one month for the next time.



  1. Exhaust black smoke emitted from a diesel engine is carbon formed during the combustion in the form of soot.

  2. Possible causes for a diesel engine to emit excessive black smoke are :

    • Faulty injectors.

    • Restricted air intake.

    • Early or late injection timing.

    • Over fueling.

    • Wrong fuel.

    • Excessive exhaust back pressure.

    • Intake air too hot.

    • Under load - low compression.

    • Engine operating below engine operating temperature.

    • Faulty turbo charger.

  3. Remedies to reduce diesel engine black smoke emission :

    • Clean, repair or replace injectors.

    • Service or replace air filter if it is excessively clogged. Check piping/ducting and connections for obstruction and leakage.

    • Set injection pump timing to engine manufacturer's specification.

    • Set/calibrate injection pump and injectors to engine manufacturer's specification.

    • Ensure correct grade and catena rating of the fuel being used as per vehicle manufacturer's recommendation.

    • Check exhaust system for restriction, carbon built-up, etc.

    • Ensure location of air intake is not under high temperatures.

    • Ensure engine compression pressure is within vehicle manufacturer's specification. This helps checking for gasket leaks, correct valve adjust or leaks, worn out piston and piston rings.

    • Check for correct opening temperature of engine thermostat.

    • Check turbocharger for damage (insufficient boost pressure).

  4. Vehicle service maintenance

    • Carry out service and maintenance interval as per vehicle manufacturer's recommendation.

    • Maintain air intake filter system correctly by using approved air filters, and ensure that there is no obstruction and leakage of air intake ducting.

    • Use grade of engine oil as approved by the vehicle's manufacturer.

    • Change fuel filters at interval recommended by the vehicle's manufacturer.

    • Adjust engine valve clearance at intervals recommended by the vehicle's manufacturer.

    • Remove injectors, check for leakage, carbon built-up, and clean fuel delivery pump as per vehicle manufacturer's recommendation.

    • For engine fitted with turbocharger, best maintenance is to observe instruction of starting and stopping the engine as per vehicle manufacturer's recommendation.

    • Check exhaust system for corrosion and obstruction.