There are many things that can cause a car to stall while driving it. An engine is made up of many parts, and many of those parts are either governed by a computer or provide input to the computer to help it determine settings for the things it governs. Every vehicle has a fuel system and an ignition system. The computer and its sensors monitor and govern the fuel and ignition systems.
If your car stalled while you were driving it, look for an obvious reason first. Check to make sure you have fuel in the tank (if your gas gauge is working). Do not sit there and crank the car over, trying to get it to start, as you will quickly wear down the battery if it's not already bad.
The ignition system is composed of: ignition switch, neutral safety switch, security bypass, plugs, wires (if applicable) and a coil, or in the case of coil-over systems, many coils. The ignition is also tied into the computer. The crank and cam sensors tell the engine where top dead centre is. Though these sensors do not usually cause a no start, if they break, the computer will go into "limp home mode," which allows you to get the car to a service station. The car will run badly, and may stall out on you.
If the plug wires, plugs or coils are bad and are causing the engine to misfire, the engine will run rough. This may also cause the car to stall when driving. Generally, it will start back up, but it may be difficult to keep the car running.
The fuel system is composed of a fuel pump, fuel filters, and fuel injectors or a carburettor. Some cars have a throttle body---this looks similar to a carburettor and has only one or two fuel injectors in the middle of it. The injectors feed all of the cylinders. In a multi-port system, each cylinder has its own injector. Should the fuel pump go bad, the car will stall while you are driving, as no fuel is getting pumped up to the engine. Bad injectors in a multi-port system will make the car run rough, which can cause a stalling situation, but generally, the car will restart.
There are other problems that can make a car stall---in the ignition system, the fuel system or in the drivetrain. If the timing belt breaks, the car will stall. If the computer itself stops working, the car will stall. Neither item will allow a car to start back up until it is repaired.
Ford vehicles have an auto shutdown switch. The switch is in the boot. If a Ford is hit with enough force or if the car rolls over in an accident, the switch is triggered and it shuts off the vehicle. This is to prevent fuel from continuing to flow to the engine, possibly causing a fire. If you were hit in the rear and the car will not start, look for the shutdown switch in the boot. It is usually on the driver's side under the carpet.
Shut-down Feature in Dodges
Dodge vehicles have a similar shut down feature. The shut down feature in Dodge vehicles is located in the computer. It is called the auto shut down relay. It will shut the vehicle down if the vehicle rolls over. There is no way to manually turn it back on. If this switch goes bad, the only way to fix it is to replace the computer.
All vehicles have an idle air motor or valve. The idle air is governed by the computer and changes the idle. When you turn on the air compressor, you use some engine resources. This makes the idle speed on the engine drop. The computer senses this drop and sends information to the idle air to turn up the idle so the car does not stall. If this part breaks, when you slow down to a stop or to turn a corner, the car may stall.
Because the running of a vehicle is complicated, there are many more things that can cause a vehicle to stall. These are the most common things that can cause a car to stall. Other things include wiring, fuses, relays, other sensors not working properly or at all, a bad alternator or a bad battery, or an overheating problem, just to name a few.