ADI Vehicle Safety & Mechanics 1 — Questions and Answers
Question 1: What is the minimum legal tread depth for car tyres in the UK?
- 1 mm across the central 75% of the tyre
- 1.6 mm across the central 75% of the width around the full circumference (Correct answer)
- 2 mm across the full tyre
- 3 mm for front tyres, 1.6 mm for rear tyres
Correct answer: 1.6 mm across the central 75% of the width around the full circumference
The legal minimum tread depth for cars in the UK is 1.6 mm across the central three-quarters of the tread width around the entire circumference of the tyre.
Question 2: What does the engine management warning light (amber) indicate?
- Immediate engine failure — stop now
- A fault has been detected in the engine management system that requires investigation (Correct answer)
- The engine oil is low
- The car requires a service
Correct answer: A fault has been detected in the engine management system that requires investigation
The amber engine management light (EML) indicates that the engine control unit has detected a fault; the vehicle may still be driven but should be inspected by a qualified mechanic.
Question 3: How often should tyre pressures be checked?
- Once a year at the annual service
- At least monthly and before any long journey (Correct answer)
- Only when a tyre appears visually flat
- Every 10,000 miles
Correct answer: At least monthly and before any long journey
Tyre pressures should be checked monthly and before long journeys; under-inflated tyres cause increased fuel consumption, uneven wear and can overheat, potentially causing a blowout.
Question 4: Anti-lock braking system (ABS) is designed to:
- Stop the car in a shorter distance than manual braking
- Prevent wheel lock-up under heavy braking, maintaining steering control (Correct answer)
- Replace the need for pumping the brakes
- Only assist on ice
Correct answer: Prevent wheel lock-up under heavy braking, maintaining steering control
ABS modulates brake pressure to prevent wheel lock-up, allowing the driver to steer while braking hard; it does not necessarily reduce stopping distance but maintains directional control.
Question 5: Which fluid level should be checked as part of routine vehicle safety before a long journey?
- Engine oil level only
- Engine oil, coolant, brake fluid, power steering fluid and screenwash (Correct answer)
- Engine oil and fuel only
- Only fluids that have a warning light
Correct answer: Engine oil, coolant, brake fluid, power steering fluid and screenwash
Before a long journey a driver should check all fluid levels: engine oil, coolant, brake fluid, power steering fluid (if applicable) and screenwash, as well as tyre pressures and lights.
Question 6: Electronic stability control (ESC) helps prevent:
- Aquaplaning on wet roads
- Skidding and loss of control by automatically applying brakes to individual wheels (Correct answer)
- Tyre blow-outs at high speed
- Engine overheating
Correct answer: Skidding and loss of control by automatically applying brakes to individual wheels
ESC monitors the vehicle's direction versus the driver's steering input and automatically applies individual brakes to prevent slides and loss of control, particularly in cornering.
ADI Vehicle Safety & Mechanics 1
What is the minimum legal tread depth for car tyres in the UK?