How Much Is a Diagnostic Test?

Strange noises, warning lights, and decreased performance can leave drivers feeling lost and confused. A full engine diagnostic test can help you determine the exact problem. One question looms large: how much does a diagnostic test cost?

In fact, the price may vary depending on multiple factors. Here are some insights on car diagnostics and its financial side.

What Is a Car Diagnostic Test?

A car diagnostic test is a comprehensive examination of your vehicle’s electronic systems. This test is designed to identify your car issues and problems and find out how long ago they appeared. Simply put, it’s a “full-body scan” for your car that involves using specialized tools and software to determine the part of your vehicle that needs to be repaired. Here’s how it works:

  1. When your car’s powered on, a technician activates specialized software.
  2. The software monitors multiple components, such as the brakes, engine, transmission, and more, and creates a diagnostic check report.
  3. By analyzing these reports, an auto repair specialist can better understand what’s wrong with your car.

Think of it like this: when you feel unwell, you visit a doctor who checks your temperature, blood pressure, and other vitals. Similarly, a car diagnostic test acts as your mechanic’s diagnostic tool, providing valuable clues about the health of your engine. By pinpointing the root cause of problems, a diagnostic test can save you time and money in the long run. 

How Much Does a Car Diagnostic Cost?

The average car diagnostic cost is about $83. Below are tables with references.

Based on the type of car diagnostic test:

Car Diagnostic TestPrice

Depending on the car make and model:

Car MakeEstimated Cost
Audi$110 to $139
BMW$110 to $139
Buick$88 to $111
Cadillac$88 to $111
Chevrolet$88 to $111
Ford$88 to $111
GMC$88 to $111
Honda$88 to $111
INFINITI$110 to $139
Jaguar$119 to $150
Jeep$88 to $111
Land Rover$119 to $150
Lexus$110 to $139
Lincoln$110 to $139
Mazda$88 to $111
MINI$101 to $128
Nissan$88 to $111
Porsche$119 to $150
Ram$88 to $111
Toyota$88 to $111
Volkswagen$101 to $128

Ways to Cover the Cost of a Car Diagnostic Test

Even if the “Check engine” light comes on in your vehicle all of a sudden and takes you by surprise, it’s better to visit a dealership as soon as possible. By taking timely measures, you won’t let a problem grow bigger. Find it difficult to pay for a car diagnostic on your own at the moment? Options for extra financing exist.

Many services accept credit cards, allowing you to put the diagnostic cost on its balance. You can also consider getting a bad credit loan with guaranteed approval or ask a diagnostic service or dealership for an extended repayment plan. This way, you might repay the cost in several installments without charging any fees.

For bad credit loans, please note that that there are pros and cons to consider before taking these loans. Sometimes high interest rates can cause individuals to go into a financial hardship.

Factors That Affect a Car Diagnostic Test Cost

The average car diagnostic cost can vary significantly, depending on several factors. Here are some key parameters that affect the price:


Diagnostics tend to be more expensive in city centers due to higher operating costs for shops. Rural areas generally offer lower prices. Additionally, regions with higher living costs often see higher diagnostic fees due to factors like higher technician wages and shop overhead.

Your Mechanic’s Experience

Seasoned technicians always have a wealth of knowledge and expertise. Therefore, their diagnostic services might cost more but potentially offer quicker and more accurate diagnoses. Junior technicians may charge less, but the diagnostic process might take longer or require additional supervision, which can potentially affect the inspection cost.

The Make and Model of Your Vehicle

Diagnostics for luxurious vehicles often require specialized equipment and expertise. This leads to higher fees compared to mid-range and budget makes. But even within the same brand, the cost may vary depending on the car model and year. More complex vehicles with advanced computer systems often require more sophisticated diagnostic tools, impacting the price.

According to the FINN data, here are the most expensive car makes for a diagnostic:

  • Audi;
  • BMW;
  • Lincoln
  • Porsche;
  • Land Rover;
  • Lexus;
  • Infinity;
  • Volkswagen.

Additional Factors

A few more factors that can affect the cost of diagnostics include:

  • Shop’s pricing structure. Some shops charge a flat fee, while others bill by the hour.
  • Type of diagnostic test. Basic scans are cheaper than advanced tests requiring specialized equipment.
  • Included services. Some shops offer additional services like reporting or repair estimates within the diagnostic fee, while others charge extra.

What Does a Full Diagnostic Test Include?

A full diagnostic test, also known as a comprehensive or advanced diagnostic test, delves deep into your vehicle’s electronic systems to uncover any underlying issues. It’s like getting a complete medical checkup for your car, providing a detailed picture of its overall health. Here’s what you can expect from a full diagnostic test.

Reading and Interpreting Diagnostic Trouble Codes (DTCs)

The mechanic will use a specialized scan tool to connect to your car’s computer and extract DTCs. These codes act as error messages, pinpointing specific areas where the system has detected a problem. The mechanic will then interpret these codes using their knowledge and reference materials to understand the nature of the issue.

Analyzing Sensor Data

Your car is equipped with numerous sensors that continuously monitor various engine parameters, such as:

  • Airflow;
  • Fuel pressure;
  • Oxygen levels;
  • Engine temperature.

The diagnostic test will collect and analyze this data to identify any unusual readings or trends that might indicate a problem.

Evaluating System Performance

The test goes beyond just reading data. It also assesses how different engine components are functioning in real time. This might involve checking things like fuel injector operation, ignition system timing, emissions output, and battery health.

Additional Checks

Depending on the shop and the specific concerns you have, the diagnostic test might also include:

  • Visual inspection of the engine and other components;
  • Road test to assess real-world performance;
  • Testing specific systems like the brakes or electrical system.

Keep in mind that the exact scope of a full diagnostic test can vary depending on the shop, your car’s make and model, and the suspected issue. It’s always recommended to inquire about the specific procedures and tests included before agreeing to the service.

Car Diagnostic Benefits

A car diagnostic comes with several benefits. It can:

  • Prevent minor issues from escalating into major repairs. Early detection often leads to more affordable fixes.
  • Help mechanics diagnose problems accurately. No more guessing games, leading to targeted repairs instead of shotgun approaches.
  • Improve your car’s performance and fuel efficiency. Addressing underlying issues can optimize your engine’s operation.

Is It Possible to Get a Free Car Diagnostic Test?

Most dealerships charge a diagnostic fee for car testing. However, you may find shops that offer free tests if you then buy their repair services. For example, Firestone Complete Auto Care offers a Free Code Scan service. It’s an informational tool that involves connecting to your vehicle and retrieving the codes that are triggering your light to illuminate.

Just keep in mind that some repair shop owners might want to make money on you. This way, they will try to use your car diagnostic test to convince you that your car trouble is catastrophic and inflate the repair cost. Be sure to work only with reputable dealers and repair shops, and always check customer reviews before visiting one.

When Do I Need a Car Diagnostic Test?

Although many drivers are quite skeptical about an automotive diagnostic service, getting one is never a bad idea. Mechanics recommend performing a car diagnostic test quarterly. Still, most drivers only bring their cars for testing if there are any malfunctions or the “check engine” light flashes.

A car diagnostic test may be necessary if you’re going to buy a used car. This way, you will have a clear picture of the vehicle’s state. If your car is already quite old, try to perform a car diagnostic at least once a year. Sometimes it may be cheaper to pay a fee for a check and prevent some troubles that might otherwise result in a higher repair cost.

Bottom Line

While a full engine diagnostic test shines a light on your car’s inner workings, its price tag can vary based on various factors. Location, mechanic expertise, and your car’s make, model, and year all play a role. Understanding these factors will help you navigate the diagnostic landscape and make informed choices.

Remember, the cheapest option isn’t always the best. Consider the mechanic’s qualifications, the test’s depth, and any additional services offered to ensure you get the most out of your diagnostic journey. After all, a healthy engine is a happy engine, and a well-informed driver is a confident one.

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