Garage Speak - Garage jargon glossary



Do you often find yourself at your local garage, nodding blankly while a technician uses words and phrases you don’t understand?

We know that the terms used at garages can sometime be confusing, but we’re here to help. We’ve created a glossary of the common terms you’d hear at a garage, including what they mean and why they’re important.

Halfords is famous for straightforward trusted advice, but to ensure everything is crystal clear, we’ve collaborated with the Plain English Campaign to keep everything as clear as possible.

While we’ve done our best, remember this glossary is only a guide. If you’ve got any concerns or questions about your car, you should always take it to a trustworthy garage for a professional inspection.

The technician says: "Your cambelt needs changing"
What do they mean?

The cambelt (or timing belt) needs to be replaced which essentially is a large, strong rubber toothed belt that connects major moving parts of your engine.

What you need to know
All manufacturers recommend that you change the cambelt after either a certain number of miles or a certain number of years. Check your owner's manual to see when yours is due, as this is an essential job that must be done as it can cause significant damage to your engine. If you're advised that the belt needs changing before this time, ask the technician to explain why.

The technician says: "Your big end has gone"
What do they mean?

A large bearing (semi-circular sleeve of metal inside the engine) has worn out and failed. This usually results in further damage to other parts of the engine. If the big end is worn it can make a loud knocking noise, especially when you accelerate.

What you need to know
Big ends are tough and rarely wear out. Because of this, any problem that has led to this diagnosis could actually be caused by a simpler problem. Ask the garage to explain their diagnosis as this problem is very rare in modern cars.

The technician says: "Your little end has gone"
What do they mean?

A small bearing that fits in the connecting rod attached to the piston has worn out. You will hear a light knocking noise from the engine.

What you need to know
Like the big end, the little end is rarely the cause of any problems, so ask your garage to explain their diagnosis.

The technician says: "The clutch is slipping"
What do they mean?
Part of the clutch mechanism which allows you to change gear smoothly is so worn it is not working properly. When you select a gear, your car will still feel like it's in neutral or, when you accelerate, the engine revs but the car doesn't go any faster.

What you need to know
Clutches are rarely repaired so you'll probably need a new one. Some technicians may suggest the gearbox also needs to be repaired or replaced at the same time. This is unlikely so always question this suggestion rather than letting the technician do it as a matter of course. If the clutch has been slipping for some time, the flywheel (a mechanical device that helps drive the engine) may also need to be replaced or skimmed (similar to the way a carpenter planes wood to produce a smooth surface). Remember, if in doubt, ask for an explanation.

The technician says: "Your sump is dripping"
What do they mean?

The sump is the oil pan that sits at the bottom of the engine, nearest the ground. Sometimes the seal on the plug that allows oil changes to be done can fail, causing a leak.

What you need to know
Leaking oil is hardly ever a major problem - usually a small part called the drain plug washer simply needs replacing. In some cases the sump gasket (the seal between the sump and the engine) may also have failed, so have the causes investigated but never ignore an oil leak as an engine with too little oil can quickly become damaged.

The technician says: "Your engine is misfiring"
What do they mean?

Your engine isn't running as it should be. It may jerk when accelerating and can often cut out when pulling away.

What you need to know Engines can misfire for a number of reasons so the garage will need to investigate the causes. It could be something as simple as worn spark plugs, or faulty sensors - devices that measure your engine - may be to blame.

The technician says: "Your fan belt is screaming"
What do they mean?

Either the belt that drives the alternator (see electronic systems below) or the fan which cools the radiator is slipping, causing friction, and making a high-pitched noise when you press the accelerator or when weather conditions are damp.

What you need to know
Most of the time it's best to simply fit a new fan belt. However, sometimes they may simply need adjusting, so it's worth asking as it could save you money.

The technician says: "Your head gasket's gone"
What do they mean?

The seal between the main engine casing (known as the cylinder block) and the cylinder head (a cast iron or aluminium cover at the top of an engine) has cracked as a result of wear and tear, leading to internal engine leaks.

What you need to know
If your car is modern, the cause of the problem is unlikely to be with the head gasket. Ask your technician if he or she is sure there isn't anything else that may be responsible for the problem.

The technician says: "We need to do a pressure test"
What do they mean?

Pressurised liquid needs to be pumped through the cylinder head to check for cracks or leaks. This is because small cracks caused by overheating are not always easy to see.

What you need to know
This method is often used to identify any problems before refitting the cylinder head. It's a specialist job, often contracted to a specialist engineering organisation to do.

The technician says: "Your cylinder head needs skimming"
What do they mean?

The cylinder head (see above under 'Your head gasket's gone) has overheated and may be distorted and is no longer sealing correctly. It is sometimes possible to grind the surface down by machine so that it fits into place correctly.

What you need to know
This can be a cheaper alternative to replacing the cylinder head. Again, this is a specialist job and is often contracted to a specialist engineering organisation.

The technician says: "You have 'mayonnaise' (or 'sludge') under your oil filter cap"
What do they mean?

There's a thick, white substance under the oil filler cap that may indicate a problem with the head gasket. The sludge is caused by water or condensation mixing with engine oil.

What you need to know
It's likely your head gasket will need replacing; ask your technician if he or she is sure that there isn't anything else that may be responsible for the problem.

The technician says: "Your brake pads are worn"
What do they mean?

Brake pads are small metal-backed plates with a friction material on the surface. They push against a metal brake disc when you press the brake pedal (see below) to slow or stop the vehicle.

What you need to know
Worn brake pads will need to be replaced or the brakes will not work effectively. It can also mean that other parts (like the discs) may become damaged. Their life span depends on a number of factors including your driving style (if you brake a lot or brake heavily) and weather conditions. Always replace the pads with those recommended by your manufacturer.

The technician says: "Your brake discs need replacing"
What do they mean?

The brake discs are metal discs the brake pads push against when you press the brake pedal.

What you need to know
While braking systems are designed so that the pads wear first, the discs can also wear down and need replacing from time to time. Discs can be damaged if pads are allowed to completely wear out, so it's a false economy to skimp on replacing them when they are worn.

The technician says: "Your ABS isn't working"
What do they mean?

There's an issue with your anti-lock braking system. This is the safety system that helps to prevent the wheels from locking up when you are braking.

What you need to know
Modern antilock brakes are far more reliable and less likely to need repairing than the older systems. Problems are often caused by dirt or rust getting into the sensors, which activates the ABS light and shuts down the system. This means that repairs can be simple if the garage investigates the problem correctly.

The technician says: "Your dampers are worn"
What do they mean?

One or more of the dampers - more commonly known as shock absorbers - need replacing.

What you need to know
Dampers are a part of your car which suffer a tremendous amount of wear and tear. Because of this they can need replacing from time to time. Worn dampers can be dangerous - they prevent your tyres from connecting with the road surface properly. This increases your stopping distances and significantly affects your car's ability to hold the road (in other words you are more likely to skid). Not replacing them can be a false economy. If your dampers are very worn, they can cause complicated parts of the suspension and steering to become damaged.

The technician says: "Your wheel cylinder is leaking"
What do they mean?

The wheel cylinder - a part of the braking system that puts force on the brake drum to slow and stop the vehicle - is leaking hydraulic fluid.

What you need to know
Leaking cylinders will affect the performance of the brakes and should be investigated as soon as possible.

The technician says: "You have a hydraulic leak"
What do they mean?

Your vehicle is losing hydraulic fluid, normally from the power steering system, which could be extremely dangerous. If the system drains of fluid completely, it will stop working and the steering will become stiff.

What you need to know
Like the human body, most car problems have physical symptoms. Ask the technician to show you the problem on the vehicle so you are comfortable in knowing what work is needed .

The technician says: "You have a hydraulic leak"
What do they mean?

Your vehicle is losing hydraulic fluid, normally from the power steering system, which could be extremely dangerous. If the system drains of fluid completely, it will stop working and the steering will become stiff.

What you need to know
Like the human body, most car problems have physical symptoms. Ask the technician to show you the problem on the vehicle so you are comfortable in knowing what work is needed .

The technician says: "Your brakes are 'spongy'"
What do they mean?

Your brakes aren't operating properly. It doesn't feel like there is much resistance when you press the brake pedal - usually because of a loss of brake fluid.

What you need to know
The leak must be identified, fixed and the faulty part replaced, or the brake fluid may need changing. Many manufacturers do recommend replacing the fluid every two years so you should check your owner's manual for specific recommendations.

The technician says: "The bushes on the wishbone are going"
What do they mean?

The rubber parts on the wishbone known as the bushes, which are part of the suspension system have either worn out or are wearing out.

What you need to know
As they are rubber, bushes can crack and perish and need replacing. Worn bushes can lead to a lot of noise from the suspension and steering as well as affect how the suspension and steering work.

The technician says: "Your wheels need balancing"
What do they mean?

The car's wheels are unbalanced. This can cause the steering wheel to vibrate when you are driving at high speed.

What you need to know
Most wheels and tyres have slight imperfections, which cause a vibration at certain speeds. These imperfections are countered by using small lead weights fixed to the wheels - a simple and quick task for a competent technician with the right equipment.

The technician says: "Your tracking is out"
What do they mean?

Tracking refers to the front wheels being in line, as shown in the manufacturer's specifications.

What you need to know
Most wheels and tyres have slight imperfections, which cause a vibration at certain speeds. These imperfections are countered by using small lead weights fixed to the wheels - a simple and quick task for a competent technician with the right equipment.

The technician says: "You need a tune-up"
What do they mean?

The engine is producing less power than it should and is not responding correctly when you accelerate.

What you need to know
Most of the tasks that we generally think of under the heading of 'tune-up' are now handled electronically using the engine management system - an electronic 'brain' that controls the engine. Ask the technician what specifically needs doing before agreeing to any work.

The technician says: "We need to run a diagnostics check"
What do they mean?

The garage needs to connect your car's engine management system to a computer which can read the information, so they can identify the source of any problems.

What you need to know
Modern cars have incredibly complicated electronics systems that manage a variety of different aspects of the car's performance and function. Not all garages have the equipment - known as 'diagnostics' - needed to read the information on the engine management system. This is because it is very expensive equipment for a garage to buy and maintain. Always check they have the kit needed for your particular make and model of car.

The technician says: "We need to access the 'CAN-bus'"
What do they mean?

This is jargon for the electronic system that allows the vehicle's engine management computer to 'talk' to different parts of the car.

What you need to know
If a technician is using diagnostics software, they can have access to the 'CAN-bus' so they can identify and fix specific problems. If a technician hasn't got the right equipment or is dishonest, they will not use this information and simply change parts until the problem is fixed - an expensive process for you!

The technician says: "The EML is on"
What do they mean?

'EML' is jargon for engine management light. This is a warning light that appears on the dashboard to let you know about a major problem with the engine or systems.

What you need to know
The engine management light can come on for a number of reasons so you need to take your car to a garage with the diagnostics equipment which can connect to the engine management system. Only a garage with these tools can diagnose the problem and reset the light.

The technician says: "Your alternator needs replacing"
What do they mean?

The part that constantly recharges the battery while you are driving is faulty, meaning the electrics on the car have stopped working, or will soon do so.

What you need to know
Alternators can be placed under stress by an old or partially charged battery, and failure is a common fault in cold weather. You should always ask the technician to check the battery is healthy as this could be the cause of any problems rather than the alternator itself.

The technician says: "Your service light is on"
What do they mean?

Many modern cars tell you when a service is due by lighting up a warning light on the dashboard.

What you need to know
Never ignore this light! Regular servicing increases the efficiency of your car and means it will last longer. Keeping to a servicing schedule is usually a condition of any warranty.

The technician says: "The catalytic converter is clogged or worn out"
What do they mean?

The device used to reduce the harmful nature of engine emissions in the exhaust system is not working correctly.

What you need to know
Also known as the 'cat', the catalytic converter can become worn or blocked over time. A problem here can also show that there is a fault elsewhere in the engine so you should not ignore it. Catalytic converters may seem expensive, but they are essential to your car running efficiently and reducing the amount of fuel you use.

The technician says: "The exhaust is blowing"
What do they mean?

There is either a hole or crack in your exhaust system, preventing it from working properly and leading to it making a louder noise than normal.

What you need to know
Over a period of time the exhaust system will need to be replaced. However, sometimes it may just be a part that needs replacing. Always ask to see the hole or crack and for an honest opinion on the best action to take.

The technician says: "Your car failed its emissions test"
What do they mean?

The emissions test is part of the MOT test. A failure means that your car is releasing too many pollutants.

What you need to know
The emissions test is a good indicator of other problems within the engine and exhaust system. Poor emissions are a sign that the engine is not running efficiently and is burning more fuel than it needs to. Normally a service will identify any issues which may need attention.

The air-conditioning filter needs replacing as it is either full of bits (often dust and leaves), or just simply blocked.
What do they mean?

The device used to reduce the harmful nature of engine emissions in the exhaust system is not working correctly.

What you need to know
A clogged filter will not only prevent clean, cold air reaching the inside of the car, but can actually stop the air-conditioning system from working altogether. If you suffer from hay fever or allergies, you should pay particular attention to your air-conditioning filters as a clean filter will dramatically reduce the amount of pollen which gets into the car.

The technician says: "You need a re-gas"
What do they mean?

Air-conditioning systems contain a pressurised refrigerant gas that cools the air as it enters the cabin. The system naturally loses pressure over time, or can spring a leak.

What you need to know
Low pressure in the air-conditioning system means it won't be working efficiently. Re-gassing is a simple and low-cost procedure that should be done every year or two as part of an air-conditioning service. Get the technician to also check that the seals are in good condition. They can do this by using a dye in the system to check for leaks.

The technician says: "Your air con needs cleaning"
What do they mean?

Bacteria can build up within an air-conditioning system, leading to an unpleasant smell.

What you need to know
A good-air conditioning service will include a process that removes extra moisture from the parts and gets rid of any bacteria.

The technician says: "Your car passed its MOT, but here's the advisory sheet"
What do they mean?

If your car passes its MOT, the garage may give you an advisory, or 'amber', sheet. This will point out items that may be worn and will need attention soon to prevent bigger problems or, perhaps, your car failing its MOT in the future.

What you need to know
You should keep an eye on any issues identified in an advisory or amber sheet and ask for them to be included in any service schedule. If your car is not due for a service, ask the technician when the items should be checked again. Do not leave them until the next MOT.

The technician says: "You need a service"
What do they mean?

Your car is due, or is overdue, a minor or major service. You need both services at different stages of a car's life. See your owner's manual for details of what's right for your car.

A minor service generally refers to oil and filter change and a visual check of the major parts. A full or a major service includes a much more thorough check of the car. Parts which wear out with use are replaced during this service.

What you need to know
A regularly serviced car will be more efficient, less prone to breakdowns and will last longer. Servicing within certain mileages or years is also a typical condition of a warranty.