How Often Should You Get A Car Diagnostic Test?

Your car runs well, there are no strange sounds or issues, and it gets you from Point A to Point B. That means everything is fine and dandy, right? Not necessarily.

There could be a small problem lurking somewhere within your vehicle’s engine or systems that’s not immediately obvious. But as you keep packing on miles, this insidious problem will keep getting worse. When you finally notice it, your car may no longer be in safe, drivable condition.

But the good news is that you can catch problems early with a car diagnostic test. This test analyzes the vehicle’s engine through the engine control unit (ECU) — its central computer. Read on to learn how often you should get a diagnostic test and what the test entails.

How Often Should I Get My Car Diagnosed?

First things first, how often does your car need a diagnostic test? Well, this first question is also the most difficult to answer.

Strictly speaking, your car doesn’t need a diagnostic test. Unlike brake repairs or oil changes, the test doesn’t actually maintain any single-safety or operating-critical component. It simply probes your car’s systems for any possible stealthy issues.

That said, it’s still a good idea to get a car diagnostic test at least annually. If you really want to stay on the safe side, a quarterly computer system check isn’t too much.

This way you’ll ensure that every system and part in your car is functioning as usual. You’ll also save money by not having to resort to emergency repairs and roadside assistance.

Situations Where You Need a Diagnostic Test

Apart from the annual tests, there are certain times outside the regular schedule when a diagnostic service is in order. If you encounter any of the below situations, bring your car in for a check.

  1. The Check Engine Light Comes On: We all hate to see it, but the Check Engine light can alert you about serious problems. If it — or any other warning light — turns on, don’t delay getting a Check Engine light diagnostic.
  2. Engine Issues: Does your engine perform poorly, backfire, smoke, or burn fuel unusually quickly? These all are signs of engine issues that need to be diagnosed.
  3. Strange Noises: You know what your car should sound like. If you start noticing any weird sounds — like grinding, whining, rattling, or clanking — your engine might be in trouble.
  4. Bought a Used Car: When purchasing a used vehicle, insist that the dealer do a diagnostic test before you hand them any money. If they refuse, you’ll probably want to buy your car elsewhere.

What Exactly is a Diagnostic Test on a Car?

If your car was built in the last three decades or so, it will be heavily computerized. You might not think so, but there’s an entire network of chips and sensors in your vehicle that constantly track the performance of its engine.

Although computers can always glitch, this degree of computerization is a huge benefit to technicians. During a diagnostic test, they tap into the car’s computer systems to identify any problems the ECU hasn’t caught.

That said, your car’s computer won’t clearly tell the technician, “My transmission is failing.” Instead, the technician will interpret a number of performance reports to identify the most likely problem. 

Because diagnostic tests require expert knowledge and specialized equipment, it’s best to bring your car to a professional auto service shop for testing.

Which Parts Will Technicians Test?

Car computer systems have advanced greatly in a relatively short time. As a result, technicians can now identify problems with many different components and systems through a car’s computer. During a diagnostic test, they will check for:

  • Problems with the engine and any other individual components the computer monitors
  • Issues with transmission or brake systems
  • Damage or wear in major components, like the throttle, ignition, or fuel injector
  • Wear or contamination in the exhaust system that could be a problem in emission tests
  • Engine oil and coolant levels

The diagnostic test gives technicians a solid idea of the overall health and condition of your car. But it can’t check for every possible issue. For example, depending on the age and make of your car, it may not be able to identify things like worn brake pads or whether you need wheel alignment.

What Happens During a Diagnostic Test?

In short, technicians connect to your car’s computer system to identify hidden problems when they run a diagnostic test. Naturally, the full process is more involved than that. Although different car service shops have different working methods, the basic workflow looks like this:

  1. The technician connects a scanner to your car and begins the test.
  2. Your car will feed any possible error codes to the scanner for the technician to analyze and interpret.
  3. The technician uses their expertise to identify the areas of the car that need attention.
  4. After locating the problem areas, the technician will physically inspect them to discover the root cause of the problems.
  5. If your car needs work or repairs to fix the problems, the technician will consult you on what needs to be done.
  6. After the repairs are finished, the technician may run an additional diagnostic test to ensure the error codes are gone.

How Long Does a Car Diagnostic Test Take?

On average, a car diagnostic test takes about an hour to an hour and a half. But this is just a rough guess because it’s very difficult to accurately estimate how long an engine diagnostic test takes.

Getting the error codes from your car’s computer usually only takes a few minutes, but that’s just the beginning. The codes won’t tell technicians exactly where the problem is, so they’ll have to check the most likely areas using their own two eyes.

Depending on the issues they discover and the extent of repairs they need, the length of the diagnostic test could stretch to several hours or even days. Here are some things that could cause the test to last longer than about an hour:

  • Extensive damage or wear to your car
  • The number of issues
  • The technician’s unfamiliarity with your car’s make or model
  • Difficulty in identifying the root cause of error codes

How Much Does the Test Cost?

As is usually the case with car maintenance services, it’s very difficult to say how much you’ll have to pay for the diagnostic. The national average price for diagnostics is about $100, fluctuating up or down by $50.

Of course, that will only cover the price of the diagnostic service itself. If your car needs any repairs, those can add to the final cost.

Fortunately, you may be able to get a diagnostic test done completely free. Customer-oriented auto repair shops, like Advanced Automotive, can give you a free courtesy check when you bring your car in. The technicians will inform you about any issues they find and leave the choice of whether to address them to you.

5 Benefits of Getting Your Car Diagnosed

The computerization of cars has made life easier for both car owners and technicians. Running a quick diagnostic test with a handheld scanner brings great benefits to everyone involved, including:

  1. Faster and Cheaper Maintenance: Before car computers, identifying any problems with the car took a long time — and cost a lot of money. Computers have significantly slashed the time and money you need to spend on maintenance.
  2. Extended Car Life Span: Diagnostic tests help technicians catch small issues before they get out of hand. As a result, you’ll avoid catastrophic part failures that could completely wreck your car.
  3. Higher Car Performance: Regular tests keeps your car’s systems and components in optimal operating condition. Well-maintained parts get more power out of your engine and give you better mileage from a tank of gas.
  4. Improved Safety: Addressing issues in a timely manner helps keep both you and everyone around you safe on the road. With every small problem eliminated, your car won’t suddenly go out of control and potentially injure people.
  5. Better Car Care: The error codes diagnostic tests provide help technicians understand cars better than ever. They can provide you with the best possible service while also building up their expertise on specific issues certain cars might face.

Get a Reliable Car Diagnostic Test in Chantilly and Warrenton

If you live in an area with varying weather or rough roads, you’ll want to get your car diagnosed regularly. Unfortunately for your vehicle, Northern Virginia happens to be just such an area.

During the hot and humid summer months, your car internals can easily get caked with dirt and leaves, which can cause all manner of issues. In the winter, the cold weather and icy roads can also wreak havoc on your car. This is why it’s important to stay on top of problems.

Advanced Automotive offers comprehensive car diagnostics at our conveniently located shops in Chantilly and Warrenton. We’ll also give you a free courtesy check when you bring your car in. Our expert technicians will let you know if they find any issues and leave the choice of fixing them up to you.

Book a diagnostic appointment online or call us today to get your car tested.