How Mechanics Know What’s Wrong With a Car: The Truth

Today’s vehicles are more complex than ever. Advanced systems and expensive components add up to serious technology we all take for granted. If you ever wondered How mechanics know whats wrong with a car this article aims to give you some insight into a good mechanics head.

Let’s dive into the world of mechanics and uncover some of the thought processes good mechanics use to find whats wrong with a car.

The importance automotive mechanics play in the world.

Everyone needs to be a good mechanic or know a good mechanic at some point in their life. Cars, trucks, boats, tanks, planes, it doesn’t matter the vehicle type. Mechanics keep the world running.

Mechanics are the men and women that have the training, knowledge, and experience to fix the complex vehicles we need to function as a society. Without mechanics, everything stops eventually. 

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How do mechanics know whats wrong with a car?

It’s impossible to put into text exactly how a mechanic knows whats wrong with a car. However, we can gain some insight to the thought process that any good mechanic uses to narrow down issues and fix problems correctly.

Let’s get started…  

The process a mechanic uses to narrow down a problem boils down to these three simple steps. 

• Complaint
• Cause 
• Correction

The truth is mechanics don’t always know exactly what’s wrong with a car, they need to play detective and use the information they have in front of them to figure it out. This is what I love about being a mechanic. Thinking on your feet and solving complex issues is what I love. 

The list above shows the core of how a mechanic knows what’s wrong with a car. Every repair comes down to these three steps in the final analysis. A good technician follows these steps, plus uses their experience, and common sense to figure it all out. 

The three steps above compile the stages of repairing a car. This is the three-step process that dealerships and independent garages use, let’s break them down. 

The complaint: 

A mechanic knows what’s wrong with a car only after the owner of the car tells them. The customer is the first step. After all, the vehicle owner knows the car better than anyone. The customer is where the process starts. They are the ones complaining or experiencing an issue that has caused them to seek out help from a mechanic.

How does this help a mechanic know whats wrong with a car?

 One word… Information.

A good mechanic always wants to have a thorough explanation of the COMPLAINT before anything else. Without an accurate complaint, there is nothing to fix! Customers that take the time to explain issues to a mechanic as best as they can always make out better in the long run.

You have a good mechanic if they are attentive and genuinely listen to what you are telling them about your car. This is simply because good mechanics know that the more information they have about an issue, the more likely it is they will find the cause much faster. 

Don’t leave anything out, especially if the problem is intermittent, the more information your mechanic has the better chance you will have of spending less on diagnoses and getting it fixed the first time. 

If you are a mechanic reading this and are just starting in the field take note. Every experienced mechanic knows a customer complaint is the first step to fixing the car. Take the time to listen and ask the customer questions, sometimes a simple “yes, it does only make the noise on right-hand turns” or whatever information is available can help you diagnose the issue much faster and with accuracy.  

The cause: 

Now we move to the fun part, what does the mechanic do next? How does he or she know what is wrong with the car? 

This is where the skill and strategic thought of a good mechanic takes form. Using the customer’s complaint, a good mechanic has the ammo he needs to start assessing the issue properly.

• When does it act up?
• What changes?
• Do you hear any noises?

The list can go on and on but you get the point.

Good information and experience with vehicle systems and components is what helps your mechanic start to narrow down to the root cause. 

Here’s a small list of SOME systems cars have, each is unique in its own right. Each of them must work together to keep the vehicle operating correctly. 

• Suspension: Shocks, control arms, ball joints, tie rods, etc.
• Brakes: Pads, rotors, brake fluid, lines, etc.
• Electrical: CAN networks, wiring harnesses, modules, convenience features, etc. 
• Safety: SRS airbag systems, ADAS driver assistance systems, ABS, etc. 
• Engine: Internal components, cooling system etc.
• Transmission: Gearboxes, axles etc.

These are some of the bigger systems that vehicles use but every system, no matter how big can be broken down into key components, and each of these can be broken up into even smaller individual components. 

This is how a mechanic knows whats wrong with a car, they confirm the complaint, then break it down into smaller and smaller chunks.

Let’s take an example: The customer is experiencing a knocking noise over a bump and the car is handling poorly. A good mechanic will first ask the customer to explain in as much detail as possible when, how, what, etc, this issue occurs. 

Knowing that the issue is most likely related to the vehicle’s chassis is where a good mechanic starts. Rather than go off on a parts-changing spree that technician will inspect the most likely cause of the issue, starting with the chassis and suspension components. 

It really comes down to experience and training… Knowing where to look and how each system and component works in the cars of today. Common sense goes a long way here. 

What about tools?

There is one thing that a mechanic needs to fix a car and that’s tools, professional tools and equipment are the mechanic’s arsenal. It starts with knowing where to look and then using the correct equipment to narrow things down. 

Scanners DO NOT fix the car! 

A funny misconception people have is that when a mechanic plugs a scan tool into their car it instantly makes them a coffee while explaining exactly what the car needs and why. 

A scan tool is only as good as the person using it in all cases, and just like an experienced mechanic that knows a suspension knock when he hears one, the scan tool can see what he can’t within the computer network of the vehicle. 

After the codes are read and the dust settles a mechanic still only has a direction to head in most cases, what he or she does with it is what makes them a good, or bad mechanic.

The Correction: 

After all this a mechanic needs to make a call and go with what he suspects is the issue. This is all fine and dandy if the car needs brake pads or a strut, the real fun comes when the problem is intermittent, buried, and thousands to fix. 

No mechanic wants to tell a customer that the 3,600 dollar repair didn’t quite take care of the problem like we thought it would. 

You better hope you diagnosed it right.

How a mechanic fixes the car at this point is a combination of experience and clean quality work. 

Here are some tips for new mechanics.

• Take time to lay things out properly as you pull them apart, lots of time gets wasted trying to “figure out” where that nut went. My old shop teacher always said, “How you take things apart will make or break you in this trade. 
• Don’t forget the basics. I can’t tell you how many times I have seen a “green” mechanic chase a funny electrical problem just to find a blown fuse 2 hours later. I’ve done it plenty of times myself! 
• Invest in quality tools from the start.
• Develop a deep understanding of car systems and how they work. It’s hard to fix something when you don’t understand how it actually works.

Wrapping it up

It’s hard to put into words how a mechanic knows whats wrong with a car. It’s a combination of analyzing the information and using experience to narrow down the specific problem.

The truth is, no mechanic always knows whats wrong with a car. A good mechanic know what it takes to find out.