Engine Diagnostics

Annual checkups from your physician keep you in good health, right? Well, the same goes for your car—regular diagnostic tests can detect problems with your vehicle before they require expensive repairs, or worse, leave you stranded on the side of the road after a breakdown. And while many people think diagnostic tests are only necessary when the check engine light comes on, there are many benefits to taking a proactive approach to car maintenance. Here’s why:

What is a car diagnostic test?

Of all the technological advances in the automotive sector over the decades, one of the most beneficial to consumers and auto technicians alike has been the computerization of the car’s components. This helps your engine run more efficiently, for example greatly increasing the interval for changing spark plugs, and protecting expensive catalytic converters, but also helping to narrow the source of problems when they do occur. Using specialized software, car diagnostic tools quickly and accurately point to problem areas in a car’s engine or elsewhere, thanks to built-in processors, microchips and sensors. They do not, however, remove the need for regular replacement of oil, oil filter, air filter, and fuel filter. So a program of regular maintenance, testing, and repair of any encroaching issues is key to keeping your car on the road and reducing your long-term expense.

Every vehicle built since 1996 has been equipped with an On-Board Diagnostics System that monitors engine performance. Discrepancies in performance levels are reported through your vehicle’s computer system. A good maintenance program takes advantage of this available information in two ways: 

  1. At each oil change the engine computer should be scanned for any pending issues, this is easy and quick to do and we will do a quick scan for free. This will not necessarily indicate how to fix a pending problem, but it does alert that more work may be needed to avoid a costly issue. Some issues show up within the live data feed, and result in symptoms that did not turn on the Check Engine Light. For example, Slow-Cranking, Rough Idling, Stalling, Knocking, or Pinging while accelerating are all signs that you should seek Engine Diagnostics to determine the full extent of your engine trouble. A decrease in Gas Mileage and detectable Loss Of Power during acceleration are also signs of an impending engine tune-up or engine repair service.
  2. Once the “check engine” or “service engine” light is displayed, the engine computer is indicating that there is definitely a problem. A solid light indicates there is a problem you should have checked soon. A flashing Check Engine light indicates you should pull over as soon as safe and shut the engine off, usually because there is excess unburnt fuel getting into your catalytic converter and making it dangerously hot, so the car should be towed to a shop. In either case, your next step should be to seek out an engine diagnostic service. 

Engine diagnostics allow our staff to gather helpful information about the operating condition of your engine. The insights obtained during an engine diagnostic will determine the extent of suggested engine repairs. The most common diagnostic trouble codes are generated in response to malfunctions in the powertrain. Engine diagnostics and regular maintenance can help extend the life of your vehicle and improve the health of your engine. 

What areas of the car can be tested?

Diagnostic tests can reveal problems within a car’s engine, transmission, exhaust system, brakes, and other major components, as well as performance issues with the fuel injector, air flow and coolant, ignition coils, and throttle.  Similar to the way doctors use medical testing to identify health issues, our mechanics use a computer diagnostic to determine the problem with your car. 


A common misconception about Car Diagnostic Tests is that technicians can use code-reading tools to determine the exact problem that triggered the check engine light. In reality, the code tells technicians which engine or component parameters are out of range, but it does not detail the cause of the problems.  The scan is the first step. Once we scan your vehicle’s on-board computer and retrieve the Diagnostic Trouble Codes, we will work to diagnose the malfunction. This may include examining streaming data from the car while it is running, looking for irregularities in the data or failure patterns, or it may also require mechanical testing to find sources of problems or to see how the diagnostic data changes as we test various areas. From there, we’ll determine what repairs are needed to prevent engine damage and get you back on the road safely. That’s where experience and skill comes in, as the technician uses his or her expertise to diagnose the underlying problem. 

What are the benefits of a car diagnostic test?

Before the emergence of car diagnostic tests, identifying problems was time-consuming and expensive, especially considering car owners only brought their cars to mechanics after a breakdown or other severe malfunction. Now, computerized car components can detect problems long before they cause a breakdown. Diagnostic tools can also check a car’s computer system for manufacturer notifications and stored information about the car’s history, giving technicians a complete picture in order to perform the best repair possible.

How often should a car undergo diagnostic testing?

You don’t have to wait for the check engine light to get a car diagnostic test. If you hear or feel something “off,” mechanics can use diagnostic testing to uncover the problem. However, many technicians recommend taking your car in for a diagnostic check at least once a year, which will uncover minor problems that can’t be seen or heard (and that won’t trigger the check engine light). 


Diagnostic testing is also a useful tool when you’re checking out a used car. Both private sellers and professional car dealers should agree to a diagnostic test before you commit to buying, and if they don’t, that’s a sign you should walk away from the deal. We have saved many people from costly poor choices via our Pre-purchase Inspections.

Diagnostics, repairs, and so much more

At Benchmark Autoworks, we offer expert Automotive Service and Repair, including Diagnosis, Suspension work, Brakes, Oil Changes, Ignition Repair, all manner of Engine Repair, and more.  Coupled with our 24 month, 24,000 mile Warranty, we want our customers to be confident that they are being cared for, but during and after the service. Come see us about your car. 

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