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Massbrook Driving School:

Under the bonnet of your car

Whether you’re a seasoned driver or gearing up for your driving test, it’s always wise to refresh your knowledge about what’s happening beneath your car’s bonnet.

Let's break down what driving test technical checks you need to know.

First things first, please keep in mind that different car models might have variations under the bonnet. It’s a good idea to consult your car manual or your friendly mechanic to locate these items.

Brake Fluid
Engine Oil
Fuse Box
Dip Stick
Windscreen Washer
Under the bonnet

Engine Coolant Level/Reservoir

Show your examiner the coolant reservoir and explain that you’d check if the levels are between the minimum and maximum marks (or up to a single mark, if there’s one). A crucial tip: always ensure the engine has cooled down before checking to avoid burns. Carefully unscrew the tank lid to release any pressure slowly.

Under The Bonnet

Engine Oil Level

Indicate the dipstick and oil cap. To check levels, pull out the dipstick, wipe it clean, reinsert it, and then check where the oil mark sits between the minimum and maximum marks. Stress the importance of checking oil levels monthly and mention that you’d do this on a flat surface for accuracy.

Under the bonnet

Engine Oil Top-up

When you are asked about the engine’s low oil level and where to refill it, you could simply indicate the oil cap. You would then explain the process: first, remove the cap, pour in the oil until it reaches the correct level, and finally, replace the cap securely.

Under The Bonnet

Brake Fluid Level

Point to the brake fluid reservoir and mention that you’d ensure the level is between the minimum and maximum marks. Emphasize the need for cleanliness around the brake fluid reservoir to prevent dirt from affecting brake performance. Also, highlight the importance of handling brake fluid with care due to its toxicity.

Under the bonnet

Windscreen Washer Fluid

Unlike other reservoirs, the windscreen washer fluid doesn’t have specific markings. You’ll need to visually inspect the level after removing the cap. Remember, regular checks are essential, especially before long journeys.

Under The Bonnet

Fuse Box

The fuse box in a car is a vital component that contains various fuses, each designated for specific electrical circuits. It’s usually located either under the dashboard on the driver’s side or in the engine compartment. Fuses are designed to protect electrical systems from damage due to electrical faults or overloads. If a specific electrical component in the car, such as the headlights or radio, malfunctions, it might be due to a blown fuse. To check if a fuse is blown, you can visually inspect the fuses in the fuse box. If you find a blown fuse – indicated by a broken wire inside – it needs to be replaced with a fuse of the same amperage rating. It’s important to carry spare fuses in the car for emergencies, and the owner’s manual usually provides information about the location of the fuse box and the correct amperage ratings for each fuse.

Under the bonnet


The car’s battery is a crucial component that provides electrical power to start the engine and run various electrical systems, such as lights and the radio. It’s typically located under the bonnet, and you can identify it by its rectangular or square shape. To check the battery’s condition, you can visually inspect it for any signs of corrosion on the terminals or a low fluid level, though most modern batteries are maintenance-free. If the examiner asks you to check the battery, make sure the engine is off, open the bonnet, and visually inspect the battery terminals for any buildup of white or greenish residue, which is corrosion. If you see corrosion, it’s important to have it cleaned or serviced by a professional. It’s also essential to ensure the battery is securely connected and that the cables are in good condition.

Under The Bonnet

Power Steering Fluid

If questioned about how to check power steering fluid, you would gesture toward the power steering reservoir and explain that you’d ensure the fluid level falls between the minimum and maximum marks. It’s important to mention that certain cars might not have a power steering reservoir.

Under the bonnet

Car Tyres

a) Tread Inspection: Visually inspect the tire treads. They should not appear smooth or excessively worn. The tread depth should be at least 1.6 mm deep.

b) Sidewall Check: Examine the sidewalls of the tire to ensure there are no cuts, abrasions, or bulges on them.

c) Bottom Inspection: Look at the portion of the tire that contacts the ground. If it seems flattened, it indicates the tire is soft and needs inflation. The recommended pressure is around 32 PSI (pounds per square inch) for the typical family car tire.

d) “E” Marking: Verify the presence of an “E” marking on the side of the tire. This marking serves as a safety and quality indicator for tires.

This comprehensive check ensures the safety and reliability of car tires, vital for a smooth and secure driving experience.

Under The Bonnet


a) Light Inspection: To check the lights, simply turn them on and walk around the car, ensuring all bulbs are functioning.

b) Brake Light Check: When alone, you can check the brake lights by reversing towards a reflective surface and pressing the brake pedal. By looking in the rear-view mirror, you can easily identify if a bulb is not working.

c) Indicator Bulb Alert: If your indicator starts flashing more rapidly while you’re inside the car, it indicates a faulty indicator bulb that needs attention.

Regular checks of your car lights are essential for safety and ensuring visibility on the road.