Faults That Prohibit Vehicle Operation

The essentials

This topic combines technical faults for which further vehicle operation may be dangerous or prohibited. The learner should distinguish a minor defect from a problem affecting braking, steering, lighting, tyres or overall safety.

What to remember

A ‘fault prohibiting operation’ means the vehicle’s technical condition does not meet mandatory safety requirements. The most important areas are the braking and steering systems, tyres, external lighting, windscreen wipers and required equipment. In exam questions, read the wording carefully: sometimes a vehicle may be driven to a repair location under specified conditions, while with certain dangerous faults driving may not continue at all.

Listen to the explanation

Educational material; not a substitute for the current official rules.

Try questions on this topic

A small practice set from this subtopic. The full question bank and saved progress are available in your account.

Operation of vehicles is prohibited if:
  1. The remaining tread depth of tires on light passenger cars is 1.8 mm.
  2. The hydraulic brake system’s hermetic seal is compromised.
  3. In both cases.

The correct answer: The hydraulic brake system’s hermetic seal is compromised.

The correct answer is “The hydraulic brake system’s hermetic seal is compromised.”. The exact component condition and permitted limit are decisive; technical requirements differ by system. Remember the exact component and limit; numbers and conditions are decisive. The other options do not describe the exact condition or limit selected by the source as prohibiting operation in this task.

Operation of vehicles is prohibited if:
  1. The remaining tread depth of tires on trucks is 1.6 mm.
  2. The pneumatic brake system pressure gauge is not working.
  3. In both cases.

The correct answer: The pneumatic brake system pressure gauge is not working.

The correct answer is “The pneumatic brake system pressure gauge is not working.”. The exact component condition and permitted limit are decisive; technical requirements differ by system. Remember the exact component and limit; numbers and conditions are decisive. The other options do not describe the exact condition or limit selected by the source as prohibiting operation in this task.

Operation of vehicles is prohibited if:
  1. There are unintended displacements or loose joints in steering system parts or assemblies.
  2. The fire extinguisher is missing in the truck.
  3. In both cases.

The correct answer: In both cases.

The correct answer is “In both cases.”. The exact component condition and permitted limit are decisive; technical requirements differ by system. Remember the exact component and limit; numbers and conditions are decisive. The correct option includes all listed cases; choosing only one would omit another condition that the source also treats as prohibiting operation.

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