1. Ignore it and see if it turn back off.
   Cancel the stakeout and head to the mechanic.
2. Pop the hood and see if anything is leaking.
   Check to see if the gas cap is on tight.

The "Check Engine" light can come on for different reasons, but the easiest to check (and eliminate) is the gas cap. if it's loose or damaged, the car's computer will throw an error code. Make sure it's tight and see if the light goes off. Otherwise, make an appointment with the mechanic to get it looked at.

1. Call a tow truck.
   Call the bomb squad.
2. Call your mechanic.
   Identify the fluid.

Finding fluid under your car is (usually) never good. The only time your car can form a puddle without alarm is if the fluid is just condensation from the A/C compressor. Find out if the puddle is water, oil, coolant, brake fluid or something else, and the area it's coming from. This is a vital clue about what's happening.

1. Faulty workmanship
   Driving with an empty fuel tank
2. Sugar in the gas tank
   A blown head gasket

When you drive around constantly on "E," you're putting your fuel pump at risk. The fuel in the gas tank helps to cool the pump, so when the tank is eternally almost empty, heat buildup can damage the pump. Splurge for a full tank every now and then.

1. Nothing much
   The sugar turns your gas into a solid.
2. Your engine will need replacing.
   Your fuel injectors will clog.

It's an urban legend that we've all heard — sugar in the gas tank will disable your enemy's car. The truth is that sugar doesn't dissolve in gasoline and, since it is heavier than gas, it will just sit at the bottom of the tank. The worst it can do is clog your fuel filter, which traps the foreign matter and doesn't allow it to do any damage to your vehicle (that's what a fuel filter is designed to do).

1. "Someone's cut my brakes!"
   "There's an issue with the brake fluid."
2. "There's something wrong with the pedal."
   "I need new brake pads."

We're not saying the bad guys DIDN'T mess with your brakes, but the most likely option is that there is either air in the brake line or the fluid has gotten old and is absorbing water (which keeps the fluid from applying hydraulic pressure efficiently). Whatever the case, have this checked out before it becomes a more pressing issue.

1. You don't have enough transmission fluid.
   The clutch is slipping.
2. Your differential is failing.
   Bad karma is following you.

When your car's automatic transmission starts shifting unexpectedly, you hear a grinding sound and there are spikes in your RPMs, the most likely cause is low transmission fluid. Get it checked out before a bill for new transmission fluid becomes a bill for a new transmission.

1. Someone's put an egg up your tailpipe
   Sulfur in the gas tank
2. A bad catalytic converter
   A clogged air filter

When you smell sulfur while your car is running, it's not a rival detective moving in on your case. It most likely means the catalytic converter is going bad and not transforming the chemicals from the internal combustion process into less harmful gases. Eggs on the OUTSIDE of your car means you've cultivated enemies.

1. Your engine overheated.
   Your engine was running without oil.
2. Your fuel pump died.
   Your carburetor was clogged.

To get to this point, you've probably ignored some pretty clear signs — puddles of oil under your car, the oil pressure sensor lighting up on the dashboard, loud knocking coming from your engine and more. Finally, the engine just up and died, and while that's bad news for you, the mechanic probably walked away smiling, thinking about the labor bill to come.

1. Low tire pressure
   A leaky radiator
2. A faulty oil sensor
   A loose hose

If you're not chasing the bad guy — or being chased by the bad guy — and you smell burning rubber. you could have a rubber hose that's loose and is coming into contact with a hot part of your motor. You literally could be burning rubber. It could also mean you've got a leaky oil gasket somewhere in the engine. Check for hoses first; it's the easiest thing to rule out.

1. You haven't had a decent meal in three days and you're hungry.
   Your transmission is leaking.
2. You have a faulty heater core.
   Your oil filter has come loose.

The active ingredient in antifreeze — ethylene glycol — is a sweet-smelling substance, and if you're smelling it inside your car, it means you've got a coolant leak, and the heater core is a likely suspect. Also, if you're fantasizing about pancakes, be sure to eat, even if you're on a stakeout.

1. A bad valve cover gasket
   Your car has been overheating.
2. The spark plug's gap was set wrong.
   Nothing. They're supposed to be black and oily.

When the end of the plug is oily, it means oil is getting into places where it shouldn't be. One cause of this could be a faulty valve cover gasket which is supposed to seal the spark plug port. Get it checked out because oil leaks are nothing to mess around with!

1. Bad oil
   Not enough oil
2. Oil contamination
   Too much oil

Just as running your car's engine with not enough oil can be bad for it, putting too much oil in can damage the engine. The oil gets whipped by the spinning crankshaft and a yellow foam starts to form. Drain off a little, and pay attention to the manufacturer's recommended oil volume.

1. A bad fuel pump
   Bad gasoline
2. A bad intake manifold
   A blown muffler

When your car doesn't want to start and there's a whining noise coming from the gas tank, you've got a bad fuel pump. The engine might also sputter, and your gas mileage may fall like a rock. Get it checked out before it completely gives up the ghost.

1. Carbon paper
   Calipers
2. A penny
   Moxie

Stick a U.S. penny into the tire's groove so that Abe Lincoln is upside down. If part of his head is covered by the tread, your tires have more than 2/32 of an inch of tread, and they have more life in them. If you can see all of Abe's hair, however, your mechanic is shooting straight with you, and baby needs new shoes.

1. Your suspension is worn.
   The engine mount is failing.
2. The transmission is failing.
   There's something loose in the trunk.

If you notice clunking or creaking sounds as you drive, especially when you go over bumps, it means that a shock or strut in your car's suspension system is giving out, or certain elements of the system need grease. Get it checked out, and keep your ride quiet. You can't sneak up on suspects in a clunky vehicle.

1. The radiator has blown.
   The transaxle has just broken.
2. The head gasket has blown.
   Your serpentine belt just broke.

The serpentine belt runs through your engine and connects several systems, including the alternator, the power steering pump, the air conditioner and, in some cars, the water pump. If this critical belt gives way, you'll notice it first with the steering.

1. You're hitting the curbs too often.
   The camber is off.
2. Your tires are over-inflated.
   Your tires are under-inflated.

The camber of your tires — sometimes called the "angle of attack" in racing — describes the angle at which the tread makes contact with the road. If the camber is off, one side of the tire makes more contact than the other, resulting in uneven wear. If you notice this start to happen, get the suspension checked out.

1. The brake rotors
   The tires
2. Tie rods and rod ends
   The steering wheel

The tie rods and rod ends are part of the suspension system that keep your tires working together and turning with the steering wheel. If you notice that there's increased resistance when you make a turn, it probably has something to do with these components.

1. Worn mounts
   Loose belts
2. Bad muffler
   Worn spark plugs

The engine and transmission are held into place by mounts that keep them in place tight against the frame. When the rubber on these mounts wears, or if the mount is failing, the vibration of the motion of the engine or transmission will be felt in the frame — and by you.

1. The throttle
   The exhaust manifold
2. The radiator
   The muffler

The muffler helps to deaden the noise of the internal combustion process. When the muffler develops a hole, that sound quickly becomes unmuffled and your car starts to roar. Replacing the muffler is the only way to quiet the beast and get back to silent pursuit.

1. Someone's put a candy bar in your tailpipe.
   There's a coolant leak.
2. It's going to snow.
   The intake manifold has come loose.

If your antifreeze is going places that it shouldn't, that can cause all sorts of problems in your car — a sticky film on the inside of the windshield after running the defroster is one of them. Check the coolant level (after the car has cooled down) and see if the level is low.

1. Flush the braking system
   Replace the brake rotor
2. Replace the brake pads
   Get new tires

The brake pads slow or stop the vehicle by creating friction with the brake rotor. The pads will wear away over time, and you'll hear a grinding noise when the brakes are engaged that will get louder over time. Get them replaced before they start to scar or warp the brake rotor!

1. Run! It's a bomb!
   Put more radiator fluid in the coolant system.
2. Change the distributor cap.
   Change the timing belt.

The timing belt keeps the crankshaft and the camshaft in sync so your car can function properly. When this belt starts to wear, it'll make a ticking sound. If it breaks or comes loose, you'll be going nowhere. Getting the belt replaced now will save you from having to call a tow truck later.

1. You're running low on oil.
   Your car is overheating.
2. A tensioner is loose.
   Your water pump is going bad.

Belts under the hood of your car stay taut thanks to tensioner pulleys located throughout the engine. When one of these tensioners starts to wear out, the belt will become looser and start making a squealing or chirping noise. Get the tensioner repaired, and keep the pressure on the belt!

1. Too much additive in the oil
   A damaged head gasket
2. A bad oil pump
   Nothing. That's what it's supposed to look like.

The head gasket keeps the oil, coolant and other fluids from mixing within your engine. When the oil has a white foam to it, that means water or coolant has contaminated the oil system, which means a gasket has failed. Get your car into the shop pronto!

1. The distributor cap
   The carburetor
2. The gas cap
   The thermostat

Back in the old days, cars had distributor caps and points that fired the spark plugs and made the internal combustion process happen. They were fairly easy to remove, and no distributor cap meant no ignition, and the car was stuck. Modern cars have ignition coils and toothed timing wheels, which are more efficient (but make it harder to easily disable a vehicle).

1. The car's computer is faulty.
   You have a bad thermostat.
2. You don't have enough coolant in the system.
   Someone has tampered with your hoses.

The thermostat is a valve that detects when your engine has reached its operating temperature and then opens to release coolant into the system. If this valve goes bad — gets stuck open, closed, or doesn't operate correctly — it will affect your engine's temperature.

1. The intake manifold
   The exhaust manifold
2. The car's computer
   The oil pressure system

The car's computer — usually called the Engine Control Module, or ECM — controls many systems in your engine, including how much fuel to add to the air for the most efficient combustion. If this module goes bad, the system goes out of bounds quickly.

1. The car is overheating.
   The car's thermostat has failed.
2. The A/C compressor has gone out.
   The cabin has an air leak.

The A/C compressor works to pressurize the refrigerant in the system and sends it to the condenser, providing cool air to the cabin. When this part breaks down, it can make loud noises, leak refrigerant and throw other symptoms, the biggest one being warm air comes out of the vents and never cools down.

1. The accelerator pedal
   Throttle control cable
2. The carburetor
   The throttle

Over time, the throttle control cable, which attaches the accelerator pedal to the throttle, can become stretched or loose. When this happens, the pedal won't open the throttle properly and acceleration will suffer. Repairing or replacing this part should get everything moving again.

1. Modern cars don't have carburetors.
   She could hear it when you pulled in.
2. Nothing ever goes wrong with a carburetor.
   She just replaced your carburetor and it needs time to adjust.

In older cars, the fuel/air mix needed for internal combustion was created by the carburetor. In modern cars, this job has been taken over by the fuel injection system, which atomizes the fuel into a mist for better results.

1. Fuel problems
   Electrical problems
2. Coolant issues
   Exhaust issues

Every detective has his or her open-and-shut cases and cases that take a lot of deduction to figure out. Because the problem may be intermittent or affect different systems in odd ways, electrical problems in a vehicle can be some of the toughest issues to track down.

1. You've been going over some rough terrain.
   The tires are under-inflated.
2. The tires are over-inflated.
   That's just how tires wear.

If you notice that the center part of your tires' tread seems to be wearing faster than the outside edges, you've probably got too much air in the tires. Check the pressure recommended by your manufacturer, and make sure that's how much you're putting in each tire.

1. Your headlights need to be cleaned.
   Your battery is shot.
2. The headlight bulbs need to be replaced.
   The alternator is going out.

When the alternator starts to fail, your car's electrical system will start to show telltale signs, such as dim headlights, slow-moving power windows and the battery losing its charge. Get to the mechanic before the battery dies completely and you're stuck in the parking lot.

1. Warped brake rotors
   Worn brake pads
2. Bad sending unit
   AIr in the brake system

When you feel a vibration through the brake pedal when applied, it's typically because the brake rotors — the rotating discs the brake pads grab for the friction needed to stop the car — are worn or warped. If they're not too warped, sometimes they can be turned back to true; if they are too warped, they'll need to be replaced.