Everything You Need to Know about OBD Scanners

Most cars on Australian streets today have a Direct Link Connector (DLC), also called an OBD port, fitted under the instrument panel on the driver’s side. These are used to hook up On-board Diagnostics (OBD) tools and diagnose issues that appear as a ‘check engine’ warning light in the dash. The tools can tell you whether the warning sign is a trivial matter (and fixed within a few minutes) or something more serious and requires the attention of a mechanic.  

History of On-board Diagnostics Tools 

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The first versions of OBD computers appeared in the late 1960s to diagnose issues in Volkswagen cars. Later variants were used in different Japanese and American brands (Datsun and GM) and had proprietary connectors meaning they were make or model-specific. OBD1 systems were standardised in the 1980s to monitor emissions and connected to the vehicle externally. It wasn’t until the mid-1990s that inbuilt DLC connectors in US cars became mandatory and displayed a wider array of codes that could be read by an OBD2 scanner. The same systems were adopted in petrol and diesel cars in the EU in 2004 and in all vehicles in Australia and New Zealand in 2007.  

How do OBD2 Scanners Work? 

OBD scanners are simple to use. These small electronic devices connect to the vehicle’s OBD port and read fault codes stored in the car’s ECU. With the engine running, the codes are presented as a series of letters and numbers relating to different parts of the car, such as the engine, transmission, exhaust system and chassis. This is in basic code readers, whereas a more advanced OBD2 scanner can pinpoint the exact issue, suggest solutions and perform a series of tests.  

Types of OBD Scanning Tools 

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There are different diagnostic tools for cars. A basic OBD2 code reader can read and clear engine codes, run an emissions or I/M readiness test, verify the vehicle’s identification or VIN number, display live data such as current fuel use, and show the current software version the car is running.  

Full OBD scanners display basic diagnostics codes, as well as information relating to the work of oxygen sensors, run an EVAP emissions test, and initiate a self-diagnostic test to uncover data from systems and sensors that aren’t always on.  

Four-mode scanners can detect common engine faults, as well as faults in the transmission, the airbags, and the braking system. This scanner can also clear the brake warning lights in the dash when doing general brake maintenance such as adjusting brake pads, and the oil light when changing the oil.  

A full-system scanner can diagnose all the car’s systems and performs some advanced service functions such as when working on the steering alignment, bleeding the brake lines, resetting the tyre pressure monitoring system, and more.  

Bi-directional diagnostic tools are meant for pros. These build on the features and usage of a full-system OBD2 scanner, but can also conduct active tests, such as checking the performance of the brakes (without actually applying the brakes). They can also be used in ECU coding, for instance when you want to clear or cancel frustrating functions and functions that are not enabled when the car left the assembly line. They can also get updated codes downloaded via the internet to diagnose recurring issues. One step up are scanners used in car and ECU tuning, which let operators modify the programming. This is helpful when changing parameters such as engine speed, boost and fuel pressure, and cam timing when working with modified vehicles. 


Features that Make a Difference 

The codes are meaningless for most car owners unless you have a point of reference. Yes, ‘P’ stands for powertrain, but the numbers that follow can get confusing. You’ll know you have an engine or transmission problem but not much else. 

Look for scanners with detailed info selected from a comprehensive database of stored codes. This tells you exactly what the fault with the car is. Data is displayed on large, legible screens, and navigating through the menus is done with simple buttons. Most consumer-grade units are handheld or Bluetooth scanners with the latter able to relay finds and results to your phone. Both display real-time info during the diagnostics test, but some units can also show historical data, such as fuel use, average and max speeds, and time and distance travelled. This is one feature relevant for fleet owners.

Pros of OBD2 Scanners 

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You don’t have to spend thousands on the latest scanner with complete ECU programming functions. Four-mode scanners are reliable tools for everyday use and give you a general idea of the outlying repair costs.  Just having your vehicle inspected at the shop costs money, and these are expenses that the scanner lets you skip. The savings are more pronounced if you rely on one or more vehicles in your line of work. The same scanner can additionally be used across different vehicle makes and models. If you’re handy around tools, then simple problems are easily fixed.  

Scanners also let you detect minor issues before they get out of hand. Early diagnostics can save you thousands. Not to mention the hassle and time of getting the car to the nearest mechanic. In addition, problems that are hard to detect, such as worn brake components can be a safety concern that you’d want to avoid and something a scanner can pick up early on. 

Twenty years from now you will be more disappointed by the things that you didn’t do than by the ones you did do.