Car dictionary: automotive terms explained
Anti-lock Braking System (ABS)
The Antilock Braking System or ABS helps the driver maintain the steering control during hard braking. Without the ABS, a car would spin out of control when the wheels lock up during hard braking, especially on slippery surface. The ABS uses wheel speed sensors to monitor the speed of each wheel. If any of the wheels lock up during braking, the ABS quickly releases then applies the braking pressure to the affected wheel, preventing it from locking. If the ABS system doesn't work properly, you will see the ABS warning light on the dash.
An alternator supplies the electric power for the vehicle's electric systems and charges the battery when the engine is running. An alternator is attached to the engine and driven by a drive belt.
If the alternator fails, the warning light "CHARGE" or a red battery-shaped icon comes on in the instrument panel.
Alternator problems are common. If the alternator fails it needs to be rebuilt or replaced. Read more »
A ball joint is a part of a vehicle front suspension. A ball joint is filled with grease inside and sealed with a rubber boot. When a ball joint is badly worn out, it can separate causing the vehicle to lose control. Symptoms of a bad ball joint include knocking, clunking or popping noise from the front end when driving over bumps. In some cases there could be no symptoms. A ball joint can be properly inspected in the repair shop, with the vehicle on the hoist.
The blower motor is the 12-volt electric fan that provides the air flow in the vehicle Heating and Air Conditioning System. Most cars have one blower motor installed under the dash. SUVs and minivans with a separate Rear Heating and Air Conditioning System have a second blower motor installed in the rear HVAC unit. The speed of the blower motor is often controlled by a blower motor resistor. A failed blower motor may become noisy or stop working altogether.
The blower motor resistor controls the speed of the blower motor in the vehicles with a manual HVAC system. The most often symptom of a failed blower motor resistor is when the heating system fan only works at the highest speed setting. Problems with a blower motor resistor are very common in many cars; the repair is not very expensive. Read more »
Part the vehicle emission control system, the catalytic converter is installed in the exhaust, right after the exhaust manifold. Inside the catalytic converter, there is a honeycomb-like ceramic block covered by a special catalyst material. The purpose of the catalytic converter is to chemically convert harmful exhaust emissions into harmless gases. With a failed catalytic converter, the vehicle won't pass the emission test.
A charcoal canister is a part of the vehicle's Evaporative System. The Evaporative System (EVAP) prevents the fuel vapors from the fuel tank from escaping into the atmosphere. The EVAP system draws the fuel vapors from the fuel tank and temporarily stores them in the charcoal canister. A charcoal canister is filled with charcoal pellets that absorb fuel vapors. When the engine is running and other conditions allow, the fuel vapors are purged from the canister into the engine to be burned.
One of the main components of the front suspension, the control arm connects the front wheel to the vehicle's chassis. In many cars, a ball joint is built into the control arm as one piece. In this case, a control arm is replaced when a ball joint wears out. A control arm may also need to be replaced if control arm bushings wear out or a car has been involved in a frontal collision or slid into a curb. Read more »
Crankshaft Position Sensor (CKP) is the primary sensor of the electronic fuel injection and ignition systems. It determines the position of the engine crankshaft and measures the engine rotation speed (RPMs). If the sensor is not working properly, a car may stall or not start at all. A failing crankshaft position sensor often causes intermittent issues. The sensor is not very expensive and is easy to check or replace in most cars. Read more »
CV Joints are used to transfer the torque to the drive wheels, while accommodating the up-and-down movement of the suspension and steering action. The abbreviation CV means Constant Velocity. CV joints are packed with special grease and sealed by a rubber boot. If a rubber boot cracks, the grease comes out and the CV joint starts wearing quickly. The most common symptoms of a bad CV joint are the clicking noise when turning. In some cars, CV joints are replaced separately, in others as a complete drive shaft. Read more »
A drive belt runs the accessories installed on the engine, such as a water pump, alternator, power steering pump and air conditioner compressor. Most cars have a single drive belt, while others may have two or three belts. A drive belt is made of a durable material, but it wears over time. As the drive belt wears out, it may produce chirping or screeching noise. Your mechanic checks the condition of the drive belt during your regular oil changes. Replacing a drive belt is not very expensive. Read more »
In any car, an engine is supported by a few mounts that not only hold the engine in place, but reduce the engine vibration transferred to the body of the vehicle. Some engine mounts are filled with liquid to further decrease vibration. Symptoms of a bad engine mount include engine vibration felt through the vehicle and jolts when shifting gears. The engine mount replacement prices range from $250 to $900 depending on the vehicle. For many cars, an engine mount is covered by the Powertrain Warranty. Read more »
The EGR valve regulates the flow of exhaust gases in the Exhaust Recirculation System. The purpose of the EGR System is to reduce the combustion temperature to control nitrogen oxide emissions (NOx). The EGR system is operated by the engine computer. If the EGR system stops working correctly, the Check Engine light illuminates on the dash. Problems with the EGR valve are very common. Read more in this article.
In some cars, the engine idle speed is controlled by the Idle Air Control or IAC valve. For example, the idle speed is increased at a cold start or when the air conditioner compressor operates. The IAC valve controls the engine speed by allowing metered amount of air past the closed throttle. Problems with the idle air control (IAC) are often caused by carbon build-up inside the valve. Sometimes the IAC valve could stick open, other times, the carbon build-up can block the IAC valve passages. The main symptom is too high or too low idle speed, rough idle and stalling. The carbon build-up can be cleaned with a carb cleaner. If this doesn't help, the IAC valve may need to be replaced.
An intake manifold distributes the air flow evenly between cylinders. In modern cars, the intake manifold contains one or two "tuning" valves that change the air flow through the manifold depending on the engine speed and load. This helps to tune the air flow at different RPMs to achieve desired torque characteristics. An intake manifold rarely need replacement. Common problems include vacuum and coolant leaks, as well as issues with tuning valves. Read more »
Turbocharged and supercharged engines have an intercooler, installed between the turbo- or supercharger and the engine intake. The purpose of the turbocharger or supercharger is to boost the intake air pressure. Boosting the pressure increases the temperature of the intake air. To improve the engine performance and prevent the engine knock (detonation), the intake air temperature must be reduced. This is the job of the intercooler. An intercooler is installed in front or on top of the engine. In either setup, the passing air is directed through the intercooler fins reducing the intake air temperature.
Mass Air Flow Sensor is an important component of the electronic fuel injection system. It measure the amount of air entering the engine. Based on the mass air flow sensor readings, the engine computer determines how much fuel to inject. Symptoms of a failed or dirty mass air flow sensor include lack of power, stalling and the Check Engine light on the dash. Read more »
The purge valve is a part of the vehicle's Evaporative Emission Control (EVAP) System. The EVAP system traps the gasoline vapors from the fuel tank and stores them temporarily in the charcoal canister. When the engine is running and other conditions allow, the gasoline vapors are purged from the canister and burned in the engine. Installed in the engine compartment, the purge valve controls the flow of gasoline vapors from the charcoal canister into the engine. Read more »
A starter motor turns over your engine when you want it to start. It is a powerful DC (Direct Current) motor attached to the engine and connected to the vehicle's battery by thick copper cables. A failed starter motor is one of the most common reasons for a vehicle not to start. Read more »
This belt is vital to the engine operation as not only it runs the camshaft(s) but synchronizes the timing of the valve train with the piston movement. In cars with an interference engine, if a timing belt breaks while driving, the engine could be destroyed in seconds. A timing belt must be replaced in regular intervals according to the maintenance schedule. Not all cars have a timing belt, some cars use a timing chain or gears instead. Does your car have a timing belt? Read more »
Vent Control Valve (also known as vent valve or vent solenoid) is a part of the vehicle's Evaporative Emission Control (EVAP) System. The EVAP system traps the gasoline vapors from the fuel tank, preventing them from escaping into the atmosphere. Installed close to the EVAP charcoal canister, the vent valve controls the air flow through the canister. Read more »
Wheel bearing is the part that allows the wheel to rotate freely. Most cars have one wheel bearing installed at each wheel. In most cars, a wheel bearing is a sealed maintenance-free unit. In some cars, pickup trucks and vans, wheel bearings are serviceable. The most common symptom of a bad wheel bearing is a humming or rumbling noise that gets louder when driving on the highway. Read more »
The window regulator is the mechanism that slides your door window up and down. It's installed inside the door and is maintenance-free. The most common symptom of a failed window regulator is when you hear the window motor running, but the window doesn't move. Replacing the window regulator is not very expensive. Read more »