Car Diagnosis Cost


Car owners often face the possibility of a diagnostic test to find out what’s wrong or why the car is performing a certain way. Many are wary of these computerized tests because they think they are just another way for shops to make money. Actually, a car diagnosis can help figure out exactly what’s going on with your car. 

However, the diagnosis test does usually cost. The car diagnosis cost can vary from shop to shop and can either be a fixed rate or charged by the hour.  A standard test that is done as part of a regular maintenance plan can be $40 but a diagnosis that points to repairs can cost a couple of hundred dollars. 

Read on to find out what you are paying for when you get a car diagnostic test. 

What is a car diagnostic test?

A car diagnostic test is a computerized analysis of all your car’s parts and systems. Many computers exist in modern cars and your engine monitors many features and creates data reports that can be gathered by a mechanic’s computer during a diagnostic test. 

Some tests spit out lots of paper data while others push out codes. It never hurts to ask a mechanic what kind of testing system they use. Most are happy to explain it to you. 


What Is Tested?

Several components of a car are tested. This includes:

  • The engine
  • The transmission
  • Brakes
  • Exhaust system
  • Sensors
  • Major components like the ignition coils, fuel injector, and throttle. 

Tests can’t point to an exact problem but do help the mechanic narrow down issues and can help prevent problems down the road if it’s caught early. 

Read: Can You Drive a Car With a Bad Fuel Injector?

When Should You Get a Diagnostic Test?

Some warranty and service agreements stipulate when you should have a diagnostic test done on your vehicle. However, the truth is, most people don’t seek out these tests unless either they have a problem with their car or the check engine light comes on. 

In some sense, a car diagnostic test isn’t something you must have. However, mechanics can use them to speed up the repair because it helps them narrow down the problem. 

A diagnostic test can be useful if you bought a used car and don’t know its entire repair history. 

Some cars may have issues that seem like they can never be properly repaired. Something else goes out when a part is repaired or replaced. A diagnostic test can get to the root of the problem.

You can run these types of tests yourself at home if you have the right equipment and, for some, they like to do that to stay ahead of repairs by testing their vehicle quarterly. 

The most important tool if you want to test your car regularly at home is a scanner. The scanner is something that mechanics plug into the car to obtain all the error codes. 

The error codes will tell you the area of the problem, although they aren’t specific.

Read: What Does The Service Engine Soon Light In My Car Mean?

What Happens During a Test?

It takes a mechanic only a few minutes to do a diagnostic test with their software and scanner. The scanner first checks the check engine light to see what other codes are produced. These other codes could indicate exactly where the problem lies. 

Mechanics then plug the scanner into the car to read the codes. Then, they use the information from the error codes to close in on the problem. After that, they can perform repairs and may repeat the diagnostic test to make sure the code is gone. 

There are other diagnostics a mechanic may use after the basic diagnostic once they settle in on a problem area. Some of these check specific things like the engine or exhaust. 

Some mechanics have a computer that attaches to the car and they put the car on a lift to watch it as the car is tested. 

Typically, you wouldn’t be charged for these additional tests because they are considered to be part of the overall diagnostic test.

How Does a Diagnostic Test Benefit Me?

Car diagnostic tests are helpful for several reasons. They help find problems before they become big headaches. That can save you money but can also save your life.  

A diagnostic test can also look at any manufacturer notifications or information on the onboard computer system. This can assist in things like recalls or repairs. 

It could be a wise idea to have a test run on any used car you are buying, especially if it’s a private owner sale. Some car owners can cover up issues well to sell the car but a car diagnostic test would catch any make-shift fixes that you would want to know about.

A test would also allow your mechanic to tell you how much any future repairs would be and how soon they may come.


Why do mechanics charge for a test if it’s so quick?

Mechanics invest money into these scanners and are also spending their time to look at your car so they must charge for that investment. That is especially true if you decide not to get your car repaired or take it to another shop. 

It’s just a standard part of doing business. 

Are there any free car diagnostic tests?

Typically, no, there aren’t any free car diagnostic tests. Some mechanics may run a special offering a free test to compete with other shops in the area. 

Another reason they may offer a free diagnostic test is that they are a new shop and want people to try them out. 

However, most shops will charge a fee to run a car diagnostic test. Be sure to ask what the price is upfront before allowing them to do it. 

One thing to be aware of when getting a free diagnostic test is to read the fine print on any service agreements before signing. It can have hidden fees or allow mechanics to make any repairs without consulting you. Make sure you know what a free test includes.

What is a general diagnosis?

A general diagnosis is an overall review of all car components because the symptoms of a needed car repair don’t fit any one category. 

Most of the time, this type of test is run when the car owner can’t specifically describe what is going on with the vehicle and use vague terms like “it’s shifting funny” or “it’s making a loud noise.”

Can I drive my car if I’m getting it tested?

Most of the time, yes. It depends on the problem. Those who have the check engine light come or hear a random noise may be perfectly safe driving it to the mechanics to have it checked out. 

However, there may be times where a vehicle is unsafe to drive. Things like an overheating engine, brakes, or axel problems are too dangerous to take a chance on and the car should be towed. 

Read: Can You Drive With Bad Motor Mounts?

What does general diagnostics include?

General diagnostics include simple and obvious things like the battery, blown fuses, an alternator, and the coil. This is where the mechanic also depends on the car owner to be as specific as possible about symptoms so the general diagnostic can pinpoint an area where further diagnostics can be done.

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