Car Diagnostic: The Best Practice

A car diagnostic, often known as fault detection, is essential to an auto mechanic’s job to find the root causes of problems.

In general, car technicians will use a scanner tool that can read the fault code of the customer’s car.

However, the issue of diagnostics has nothing to do with any specific section of the car in particular.

Once your understanding of a car system is comprehensive, you can apply a similar justification approach for evaluating the fault, regardless of the mechanism.

Again, it’s because you have an adequate understanding of the system.

Information and Data You Will Need Regarding Car Diagnostic

There is a considerable amount of information and documentation connected to automobiles that you may access to undertake various diagnostic procedures.

Mostly they are present in books, CDs,  or DVDs. However, many are available on the internet or as a subscription.

The information is essential to ensure that you identify the problem.

However, it would help if you first gained the diagnostic abilities necessary to use it.

The following categories of data are generally readily accessible:

  • inspection and tuning of the engine
  • Maintenance and fix procedures and timings
  • gas and combustion processes
  • wiring layouts
  • part locations
  • configuration data
  • diagnostic schedules

Several fantastic bundles are purchased as part of a premium content plan.

Or you may receive them as part of a diagnostic tool.

Occasionally, you will be required to log in to a specific website.

However, once you have done so, you will have access to the equivalent content provided to the primary car dealers.

For instance, the website for a specific automobile model offered various purchase alternatives, such as complete access for an hour for a particular cost.

Know Your Limits In Car Diagnostic Process

It’s one of the abilities that are very challenging to master. But additionally, it is among the most significant aspects.

There are two parts you need to know:

  1. Recognize the limits of your capabilities. There isn’t enough time in the day or even a lifetime to excel at everything.
  2. Don’t mess with the systems in which you might potentially trigger additional harm to yourself or possible damage, such as the airbags circuits.

An individual who is a novice to diagnostics may frequently struggle to detect the problem while having the strongest of motivations.

In the procedures, they will accidentally bring other problems into the mechanism.

I advise you to become more familiar with your capabilities and limitations.

You could have a lot of self-assurance and be skilled at solving difficulties involving mechanical systems.

However, this might not be the case if circuits are present.

So again, it’ll be possible that you are the exact reverse of something like this.

It is essential to remember that diagnostic expertise consists of two components: first, an understanding of the system, and second, the competence to perform diagnostics.

Whenever you don’t understand a system, you should avoid interacting with it unless you do.

Car Diagnostic Process Guide

Before starting a car diagnostic, there are six stages that you need to know, namely:

1. Verification

At this stage, you have to make sure whether there is a problem with your car. You should also confirm the signs related to the problem.

2. Gathering information

Obtain more knowledge concerning the car’s issue by observing it and conducting research.

3. Evaluation

Take a moment to reflect on the available findings.

4. Testing

Proceed with the additional test in the order that makes the most sense logically.

5. Rectify the car problem

At this stage, you fix car problems.

6. Check

In the final stage, you will want to verify that every system is functioning correctly.

What Do You Need to Get Accurate Car Diagnostic Results?

The understanding required for accurate and consistent diagnostics may be divided into two main categories:

  1. You have an excellent knowledge of the system where the issue is present
  2. You can implement a reasonable diagnostic method.
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An Example of How Important It Is to Use Knowledge in Car Diagnostics

Following is a straightforward illustration that you may use to show both the required level of knowledge as well as the practical application of diagnostic abilities:

“There is no water coming out from the end of your hosepipe when you have connected the tap correctly and turned it on.”

Based on what you learn about such a system, you must be able to get water to flow out as long as the tap condition is turned ON.

It’s due to the pressure coming from an existing tap that will push water flows through the hosepipe.

Therefore, that’s where the ability to diagnose becomes essential.

The following steps need to be taken at this point:

  • First, check the pipe’s opening to ensure no water leaks.
  • Next, you can verify whether water is coming out of another tap? Ask yourself whether it is coming from the tap before attaching the hose.
  • Take into consideration whatever this evidence reveals to you. For instance, the hose is clogged or overtightening when your answer is YES.
  • Search the whole pipe’s lengths for a bend
  • Ensure the hose is positioned correctly.
  • Ensure that water comes out of the tap and you do not have further issues.

It is OK to simplify things quite a bit.

However, the process you have just gone through to make the hose function will also identify a fault in such a system you apply it.

It is not difficult to understand how it functions concerning a hosepipe.

Also, I am confident that anyone would have discovered that flaw, or at least most people.

The other level of expertise can adapt the similar logical process to more complicated scenarios.

Understanding the Car Diagnostic Stages Cycle

The car’s diagnostic cycle may proceed through its six steps until the issue has been identified. 

I will discuss these stages in even more detail in connection to an automobile workshop scenario more representative of real life. It’s not that figuring out why the hose won’t function isn’t a goal.

Electrical problems are sometimes thought to become the most challenging to detect, although it is not necessarily the case.

To illustrate this point, I may consider the malfunction of a car’s cooling system.

Remember that you can mechanically or electronically apply the diagnostic process for any issue.

Now, let us assume that the problem that has been documented is engine overheating.

That’s about only the info you will have to begin with, which is typical of the scenarios that typically happen in most workshops.

From this point on, you can proceed through the following six stages:

  1. First, you should look around briefly to inspect for any visible issues, like leaking, damaged drive belt, or insufficient coolant levels. Next, drive the car to verify if the problem is still present. It may be something like the heat gauge in this case.
  2. Do you know any further infor­ma­tion? For instance, does your engine get too hot frequently or only when it’s under long travel distances? Review the records, if they are relevant, of something like the earlier repair that has been conducted on your car.
  3. Think about what you understand better now. Do you also have a sounder idea of what may be causing the problem due to this information? For instance, does this make sense if the engine consistently overheats after replacing your cylinder head gasket? Please don’t allow the sum of one and one to equal three; instead, allow it to represent like a pointer. Keep in mind that throughout the field of logical diagnostics, an answer to the question one plus one equals two will always be two. Nevertheless, once you realize it for sure, you should do the best with your ability to help identify the fault.
  4. Your thought at this level, which is now being performed, would drive the following tests that are taken out. You still don’t sure if the issues are caused by a leak head gasket, a thermostat that is blocked in the locked position, or another kind of issue. In light of what you observe, the subsequent test that should be performed will most likely be a pressure check on your cooling system. Whenever the pressure rises while your engine is operating, the issue is probably a faulty head gasket or another subject of a comparable form. If there is no noticeable rise in pressure, proceed to the subsequent test, and so forth. Return to stage three after every test you take and analyze whatever you understand rather than what you do not learn.
  5. Let’s say you know the cause of the issue is a thermostat that got stuck in the open position. Now is the time to change it; you can add your coolant volume, etc.
  6. Check to see if the system is operating normally again. Also, make sure that you have never created any other issues by your actions, like leakage or broken connections.
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This illustration is oversimplified but similar to such hosepipe issues; what is essential is the order of the steps, notably the stop to analyze at stage three.

If you get a sufficient understanding of the system mechanism, you may be able to bypass the symptoms of the problem and get straight to the root of the issue around this point.

Understanding the Root Cause of Problems in Your Car

The term root cause analysis is often used to refer to various approaches to issue addressing that focus on determining the underlying factors that contribute to occurrences of problems.

Since it highlights the significance of maintaining an open mind while identifying problems and, once again, underlines the ability to think systematically and logically.

I also include some little parts since it emphasizes the value of understanding when diagnosing issues.

The underlying issue causing a vehicle issue may not always be easy to spot.

Let us imagine that the symptom was a malfunctioning of one of the rear lights on the vehicle.

Because it had a problem with an open connection, a connector component had to be changed using the six stages technique. The light is already functioning normally.

However, what’s been overlooked was that a minor leak in the pipe leading to the back screen wiper caused water to flow over the connection whenever you use the washer. It can be a fundamental problem.

In contrast to focusing only on faults that create observable signs, the root cause analysis method is based more on well-founded assumptions.

It means you can treat problems with your car most effectively by making efforts to address, repair, or eliminate the underlying cause.

It is far more probable that issues will not keep happening if the actual causes are addressed and fixed.

It is essential to think of root cause analysis as an ongoing process.

It is not frequently possible to completely stop a problem from occurring again with a particular act to repair it.

An issue’s underlying causes might lie in several aspects of an operation.

The figure known as a fishbone diagram is commonly used to illustrate this.

It demonstrates how an issue may be caused by a single event on the many branches of an operation that is sometimes quite complicated.


Car diagnostic is a necessary process that you do when you want to know for sure the causes of a problem that occurs.

By knowing the six stages of the car diagnosis process, you can learn how to do it systematically and logically.

However, the stages don’t always have to be used for checklists, but they will give you insight into how important it is to follow the process as you diagnose your car.

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