Keep exhaust gases and heat controlled
The vehicle requires an efficient exhaust silencer, and the engine’s gases must pass through it. It must not emit smoke dense enough to obstruct other road users’ vision or cause a nuisance. A disconnected or bypassed silencer is not cured by keeping engine speed low.
Position and maintain the exhaust so that fuel, oil or other flammable material cannot fall onto a hot part and gases cannot leak into the cab or passenger compartment. Exhaust heat and fumes can create danger without an obvious mechanical failure at the steering wheel.
No dangerous fuel defects
The tank, fuel receptacle, carburettor and pipes must not be defective or dangerously exposed. The tank needs an effective cap. Check an apparent leak before starting rather than hoping airflow will remove it. Do not continue operating a vehicle with a fuel system that is a source of danger.
The heavy-vehicle fuel-system rule repeated in §6.66 expresses the same safety duty. Its separate placement in the manual does not exempt motorcycles or light vehicles from the earlier general requirement.
Secure and insulate wiring and batteries
Electrical wiring and batteries must be correctly installed, insulated and maintained so that they do not create danger. A loose battery, chafed cable or exposed live connection is a defect to remedy. Keep carried goods from striking or shorting electrical components.
Cover dangerous engine parts
A light or heavy vehicle’s engine must be covered so that it is not a source of danger. Secure covers and associated bodywork before moving. The purpose is safe protection, not hiding a leak or continuing to use a defective system.
Worked situation
A loose metal tool lies across the battery terminals in a goods vehicle’s equipment compartment. Before travel, remove the short-circuit risk and secure the equipment; merely closing the cover does not satisfy safe wiring and battery maintenance.