troubleshoot car problems

How To Troubleshoot Car Problems at home in 5 steps

In Troubleshooting by Magnus Sellén2 Comments

Is your mechanic replacing the wrong parts all the time, and you just pay whatever he says? That’s because they didn’t do a good troubleshooting and they earn more money if they could replace more parts as long as you just pay them. This is a very common issue because many customers do not ask or don’t understand at all what your mechanic is doing on your car.

In this guide, I will explain to you how you can do a lot of the troubleshooting yourself with some cheap tools that you can have at home. Depending on the country, but often you pay over 100$ for a diagnose with the computer that takes them 10 minutes. You can have buy tools that are doing the same job for under 80 $ and after that diagnose your vehicle yourself, as many times as you want. I will give you tips of what tools you could buy to use at home and how to do a real troubleshooting yourself at home.



My name is Magnus, I’m working as a car technician. For most of the time, I’m doing troubleshooting on cars and searching for the most advanced faults. I’m the owner of this website, which I made to help you car owners out of how you could save some money. In this article, I will give my best tips on how to troubleshoot a car and go through the step to step about how I’m finding the faults fast at work. I will give you some advice about how you could save a lot of money by learning a bit yourself about some easy tasks that you can do at home.

Welcome and let’s go to the troubleshooting procedure.

1. Read the DTC trouble code memory

troubleshoot car problems

In almost every troubleshooting that I am going to diagnose that is related to any electrical/engine part, I am starting the troubleshooting by reading the DTC trouble code memory. Cars today are really smart and are really good at detecting problems. Directly when one of the control units sees a problem, it will save the fault in the trouble code memory. That is why you should always start by reading the faults.

The trouble codes will be stored in the memory for a very long time and at each start of your vehicle. That process is called a “cycle” and the car will test the fault every time you start a cycle. It’s a lot depending on what kind of car and control unit, but the most cars will try out the problem around 20-30 times. If the control unit can’t find the problem for 20-30 times, it will erase the trouble code automatically.
If the control unit is seeing that problem one time between the 20-30 cycles, it will start from the beginning and because of that you will have a really big chance to see the trouble code when you are using a diagnostic tool.


Many workshops are using very expensive diagnostic tools and that is why you have to pay a lot of money, even if the trouble memory search will only take 10 minutes. But in many cases that expensive diagnostic tools are not necessary.
If you are going to read the memory in the engine control unit, a cheap tool will work almost as good. The cheap tools could have a bit harder to search through all of the other control units, but in some cars, the cheap tools can do the same job. Always read the description of the product to see what cars it will work on before you buy it.

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Instead of paying the workshop over 100 $ every time they are going to check the engine DTC memory, you could buy a diagnostic tool for under 70 $ and do how many DTC memory searches as you want.

If you consider buying a diagnostic tool to have at home, there are a lot of different tools out there. A tool I can recommend is the ANCEL AD410 Enhanced OBD II Vehicle Code Reader. You’ll get a really good tool for a low amount of money. It can read and erase the DTC memory of the most vehicles in the market.


If you get a trouble code from the memory, you can take the trouble code number etc P0301 and check here if you could find it. When you got the whole trouble code name, you could either use Google or you can Ask Us and we will give you information about what the trouble code is about and what the possible causes could be.
Check out if you could find your trouble code here:
Generic DTC codes


2. Find information about the trouble code.

car troubleshooting problems

The next step is to find as much information about the problem as possible. You have to research and get the right information What is the trouble code telling us exactly? What are the possible causes and what are the causes that the control unit would save this trouble code? You can never get too much information about the trouble code.
Many people and even mechanics are just reading the first words of the trouble code and then go as fast as possible to the repair shop and ordering the part they think. That could cost you a lot of unnecessary money and just by searching some more information you could use this money for something more fun.

Searching information on the web is free and anyone can do it, so why should you hurry so much to order a part that got a 10% chance of going to fix the problem. I will show you a good example of what I’m talking about.

You read the DTC trouble code memory and you see this trouble code.

P0341 Camshaft Position Sensor Circuit Range/Performance

Many people are just seeing the words “Camshaft Position Sensor” and then ordering a camshaft position sensor.

And then take a look at this trouble code:

P0340 Camshaft Position Sensor Circuit Malfunction


It is the same trouble code, isn’t it? No, this trouble codes are completely different from each other.
The first trouble code is saying that the position of the camshafts is wrong, it could be a faulty camshaft position sensor but the chance is very small. You probably have a problem with the camshaft alignment/timing belt. What do you think will happen if you replace the camshaft sensor and after that, you keep driving it? Yes if it’s a problem with the timing belt you would not only waste your money on a new sensor, you could destroy your whole engine.

The other code is telling us that there is an electrical problem with the sensor or the wiring to the sensor. With that information, we could know that we should not start to check the camshaft timing first at least. I hope that you understand what I’m trying to say with this.  This is why it is so important to find the right information and looking what the trouble code says, it could save you a lot of money and time-consuming work.

If you cant find any good information on the web, you can ask us at this site. Send us a question and write the fault code number you get etc P0340 and write the car model and engine.

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3. Find similar cases.

car troubleshooting problem

A lot of all the problems on cars are common problems. Because the engine models are made the same, you are probably not the first person with the same problem. Find cases, where the fault has been solved before, could save you a lot of time and money. You can not always find the exact same case, but by finding similar cases you could at least get a hint of where you should start your troubleshooting. You can either search the Web or you can check our database if we have been answered any similar cases before. If you can’t find any information of similar cases, then you could send a question with as much information as possible about your fault and we can check if we could find any known problems.

In some cases, you won’t find any similar cases answered before, and then you have to find it out yourself, how you should do it I will explain in the next step.


4. Get wiring diagrams/other information

troubleshoot car problems

Now when you know what the fault code is telling us and you may have been found a similar fault, it’s time to make sure that you will replace the right part. Just guessing could be expensive and it does not cost anything to do a good research. Also here, before you are picking up your multimeter and start to just measure parts, you have to know how the parts are working and what test results you should have.

If you have a part that you are suspecting, you have to find information about that part. Find information to measure or try it out to make sure that you found the right problem. Sometimes in troubleshooting, it can be very hard to get the accurate measure values. To find good information that you can trust could be hard. But we are lucky that we got internet and there are many sites there that are offering the original repair manuals for free. Just find out the engine code for your engine and the car model and search for that + repair service manual and you will get a lot of hits.

The service repair manuals are often containing a lot of good information, how to measure or test the parts and how they should be if they are okay. They can be a bit tricky to find the information that you are searching for but once you have learned how they work it won’t be a problem. Troubleshoot all the parts that you think could be faulty several times to get a result that you could trust and when you have found it, go and find what part number you are searching for to get the right parts.
If you are searching for cheap parts for your car,  I can recommend you to check on eBay. There are a lot of both new and used parts there for a good price.

Once you think you have found the problem and got your parts it’s time to go to the next step.


5. Repair the problem and try it out

troubleshooting car problems

You can look in your repair service manual again to make a proper and a good job when you are replacing the parts. That will make the whole troubleshooting process a lot easier. When you replaced the right part or repaired it, its time to go for a test drive to make sure the problem is gone. First, before you are taking your vehicle out for a drive. You have to make sure that you cleared the DTC trouble code memory! To clear the fault memory after you have made any repair is always a good idea for both you and maybe the next owner, as I told you the trouble codes could be stored inside the memory for a long time.

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If you are not clearing the memory before you can also trick yourself after you have taken a long drive and it all worked properly, and then you are checking the trouble memory and you are still getting the same trouble code stored. After you cleared the memory, take a very long test drive. Try all possible scenarios on the road where the fault could occur. A lot of different speed and extreme situations.

I can recommend you to drive for some miles, park the vehicle on the side of the road and shut it off, pull out the key and start over. That’s because the part I explained to you before. The control units are working in cycles and some trouble codes won’t be registered before they have seen the problem in 5-10 cycles. That’s why sometimes just a very long test drive would not make the fault to occur.

If you have tested the car in a lot of cycles and think the problem is OK, then it’s time to check all fault memories again to make sure it’s clean. If it’s clean then you should have made success with your troubleshooting and probably saved a lot of money!



  • It’s always good to spend some time and make a good troubleshooting to not throw your money away.
  • Find as much information as possible about the trouble codes and repair information. It will save you a lot of money in the end.
  • Instead of wasting 100 dollars each time your workshop is going to search your trouble code memory, you could do the same job with a cheaper tool that you can have at home
  • Always start the troubleshooting with searching for trouble codes first.


I hope that you have learned something in this guide and your troubleshooting was successful. Now you can go to your workshop and tell them how to make a proper troubleshooting 😉 But at least I hope that you will save a lot of money to do some troubleshooting yourself at home. It’s always fun to learn people how to do it yourself instead of just giving the jobs away to someone that will probably not be very careful with your money and guessing the faults.

If you have any questions or want some more help of troubleshooting you can contact us here on this page to ask your questions. I would really like to hear about what you think of this article, and if you want us to add or edit something, you can comment down below here. I would really appreciate it!

See you in the next article and don’t forget to check our other articles if you want to learn some more! 🙂

Hello I'm Magnus, the owner and the writer of this website. I have been working with cars since I was 16 and I'm specialized with in-depth Automotive diagnostics. Also been driving drifting for the last 6 years. I'm here to give you answers to all your automotive questions and I hope that you enjoy our content.

  1. I’m driving a Vw Polo 2008 trendline and recently experience a misfire on my car after driving 120_140 km p/h mostly at night.During the day I don’t experience the problem.The problem disappear after the car is parked overnight and it will run/drive normal during the day.Can you please advise what can be the problem or cause.

    Thank you

    T Kiewitz

  2. I had my car serviced after engine kept overheating with constant overflow of coolant from reservoir tank. Now there is problem with cooling system where temperature gauge is locked at Cold, both fans running when ignition is switched on and won’t stop while Engine Check light remain On. Please kindly advise causes and how to resolve the problem.

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