How to Diagnose Common Car Problems

Smart Diagnostic System - OBD2 Tablet 7111 being plugged into a vehicle to complete an automotive diagnostic scan


Cars can be expensive to maintain, but it's crucial to diagnose problems before they escalate. A regular maintenance schedule can help prevent problems and increase your car's longevity, but some issues may be unexpected.

Often, you can feel, see, smell, or hear the warning signs. It is essential to use your senses to recognize these signs before an issue gets serious, expensive, or worse. 

Fortunately, these problems don't have to go unsolved. Diagnostic scanners, tools that you plug into your car, provide codes specific to your make and model to help pinpoint exactly what's causing issues. If you are having trouble figuring out where a problem might lie after looking at all the indicators visible inside your vehicle —including dashboard lights — a diagnostic scanner can reveal the problem. In combination with a repair app, you can learn the exact issue, watch DIY repair videos, or know when something requires expert help.


Feel It Out

There are plenty of warning signs in particular areas of your car you may notice and need to tell your mechanic about. One important sign is how your vehicle feels to drive. This is one of the more common indicators of a car problem. Tire wear, fluid leakages, and other issues can all be physically felt in some way when you're driving.


Innova Electronics, brakes on a car getting inspection by mechanic

If your brakes are shuddering or feeling sticky, there might be an issue with the brake pads or rotors. The brake fluid may also be low and need a refill. If the brake pedal is spongy, feels mushy, or goes to the floor when you depress it and then returns up slowly, that may be a sign of air in your brake system, or mean there's a leak in one of the lines. The valves are another vital part of brakes that could require attention if they're leaking fluid too quickly or not enough at all.

There can also be an issue with your calipers if they seize up and won't move freely anymore. This causes them to drag against parts like rotors and drums, which will cause damage over time as well as make braking difficult because more pressure needs to be constantly applied for stopping power.

Brake problems can be expensive, ranging from $100 to $300 depending on the extent of the damage and other factors, though labor costs will vary by mechanic and shop. The ability to stop your car is imperative, so you’ll need to deal with brake problems immediately. If you keep driving with faulty brakes, you can make existing issues worse.

Leaning or Pulling

Leaning or pulling when driving may be caused by a flat tire, a worn-out suspension system, or an alignment problem. A simple tire check should reveal or eliminate the possibility of a flat tire. When you are coming up on a stop sign or traffic light, and your car pulls to one side, it could be caused by an issue with the tires. To get your alignment checked, schedule an appointment with your mechanic as soon as possible.

A tire might not be as expensive to replace as an alignment, but it can cost anywhere from $50-$200, depending on the type of tire you need. A suspension system may be around $1,000-$5000, while an alignment fix is between $65-$200.


Many things can cause shaking or vibrating in a car, but the most common causes are misalignment, loose lug nuts, and worn engine or transmission mounts. Loose lug nuts on one wheel will cause that wheel to spin out of sync, increasing the wear on your tires and creating an unsteady ride. Worn mounts have lost their cushion, causing additional vibration as you drive.

Misalignment is commonly incurred from hitting potholes at high speeds (especially if you hit them while turning). Low tire pressure due to punctures or improper airflow may also lead to shaking when driving over bumps at higher speeds. These issues range in severity, and therefore, cost to repair.

Turning Troubles

If your car is having trouble turning, it could mean that the tires are worn out and need to be replaced soon, or that you may have a wheel alignment issue. There might also be something wrong with the tie rod end or ball joint on one side, which would cause more pronounced difficulty in holding the vehicle straight. Tire replacements, realignments, tie rods, and ball joint replacements are all reasonably inexpensive — ranging from $50-$200.

Failure to Start

If you are experiencing any of these problems, there is likely an issue with your engine, battery, fuel system, or starter:

  • The car won't turn on;
  • You hear clicking sounds when trying to start it;
  • Your car starts but won't stay on.

If you notice any of these symptoms, visit your local mechanic. They will determine if the issue is with the battery, engine, fuel system, or starter and provide a solution for getting your vehicle back on the road. These problems may also begin, or become exacerbated, in the winter. The winter weather may be brutal on your car, so you may want to winterize your vehicle to avoid these problems.


Use Your Eyes

Innova electronics home mechanic inspecting the underside of a car for vehicle diagnostics

Sometimes the best way to diagnose potential issues is by using your eyes. Often, you can see a flat tire, leaking fluid, or dimmed headlights. To make things easier, you also have lights on your dashboard to alert you of issues with various parts of your vehicle.

Dashboard Lights

If you see a dashboard light, it means there is something wrong with the related component — such as when your engine light comes on. The exact may not be immediately clear from the light alone, but when connected with other symptoms like abnormal sounds or smells, those lights can provide an indicator of what's going on in your car.


Tires should always have even wear across their surface, which is a sign they're in good condition. Depressions or bulges on one side could indicate damage from an object like a rock or piece of metal, while uneven tread depth indicates that your tires need replacement. If you notice bubbles around the edge of any tire, then this means there's air leaking out and needs to be patched up as soon as possible if not replaced with new ones altogether.


Puddles are the most obvious sign of a leak. If you see puddles around your car, there's fluid leaking out from somewhere and needs to be fixed immediately. Water leaks can dim headlights, leading to short-circuiting electrical devices like radios and lights on the dashboard. This is most often a sign of a faulty pump somewhere.

An oil leak can cause some expensive problems, like not being able to start the car if the engine needs oil for lubrication. They will also stain your driveway or garage floor.

Follow the Scent

Sometimes you may smell excessive exhaust, fuel, or even sulfur emitting from your car. These smells can be a sign of a range of car problems that come with an equally wide range of costs to repair. Check for the following smells to gain a better diagnosis of what's going on with your car.

Smoke or Burning

If you smell smoke or burning coming from your car, it could be a sign of a fire or other engine problems. If you're not sure which, turn the car off and call for help immediately. Smoke may also come from breaking hard or for too long or a worn clutch as well. Other minor issues that may produce smoke include blown seals and/or gaskets. Since smoke and burning smells range in severity, you must get the problem diagnosed and fixed ASAP.


A sulfur smell may be the result of bad fuel or leaky gas. You may find your battery is about to die, though a clogged catalytic converter can also create this odor. If your car emits a strong sulfur smell when idling and worsens on acceleration, it could be time for service. 


If you smell a sweet odor coming from your car, it could be a sign of coolant leaking. from your radiator or cooling system. The bubbling sound that accompanies a leak may also give away the problem. It's best to keep an eye out for these signs and have them fixed as soon as possible before they can lead to other issues down the line — such as your engine overheating.


Fuel smells are often a sign of an issue with your fuel injector or fuel tank. If you notice a strong gasoline odor coming from inside of your vehicle, there may also be contamination in the fuel tank or filter, which can lead to more severe issues like internal engine damage. The problem could also be as minor as a loose or cracked gas cap.


If you smell mold, it is likely the result of a wet carpet or floor mats. If there are any leaks in your coolant system, this will also produce an unpleasant odor that can be mistaken for something else like exhaust. Replacements for car carpets or floor mats are inexpensive and a quick fix.


Listen Up

innova electronics mechanic listening to car for noises while performing vehicle diagnostics

Your car can often tell you what's wrong if you listen to it. Banging, clanking, and even bubbling can be signs of minor to severe car problems. Pay attention and listen to your car for any of the following sounds to better diagnose what's wrong.


Squeaking can mean your timing belt needs replacing, or just needs some moisture removed. Other problems can be your power steering belt or a faulty power steering pump. One final thing to check is the brakes. Worn brake pads can squeal and screech when coming into contact with your rotor.


A creaking sound can be caused by a worn shock or suspension strut — especially when going over bumps. It may also be a sign that your ball joints and bushings need lubrication.


If you hear a banging noise, your engine may be misfiring. This can mean that your car needs its spark plugs replaced, the air/fuel mixture is imbalanced, or the ignition timing is off.


A grinding noise means your transmission may be on the verge of failure. You'll want to schedule a diagnostic with an expert immediately if you hear this sound coming from inside your engine bay. It may also mean your transmission fluid is low. Another thing you might check if you hear grinding is your brakes. Bad brakes can make this sound, but it may be the case that debris is trapped between your brake pad and rotor.


A bubbling noise coming from your radiator means a leak in one of the tubes of hoses. You may also hear it when you turn on the air conditioning if the coolant isn't circulating through the system properly. This sound can also mean a blown gasket.

Your car will often tell you when something is wrong. If you feel, see, smell, or hear any of the above, get your vehicle to the mechanic immediately. While it may be minor, you don't want to be driving around making it worse or you could end up with a costly car problem. The information above can help you better diagnose what's wrong with your car, but you will always want to double-check with a professional.