Technician using a universal OBD2 scanner

OBD2 scanners are invaluable tools when the worst happens and your vehicle’s check engine light comes on, but you have no idea what the problem is, but are OBD2 scanners universal?

We’ve all been there before: you’re driving along and in your periphery, a bright orange light suddenly appears. Your stomach drops. You glance down at the gauge cluster to confirm. Yep, it’s the dreaded check engine light.

All is not lost, though. You have a few options, including calling your mechanic or popping over to the local parts store, where associates are often happy to diagnose the potential cause for the light.

You could also buy an OBD2 scanner and begin the diagnosis yourself.1 But are they universal, or do you need to purchase one specific to your make and model?

Luckily, the answer is yes – any OBD2 scanner will plug into any car built after 1996.2 There are a few caveats, however, which we’ll get into in a moment. But first, let’s talk about what OBD2 even is.

What is OBD2?

OBD2 is shorthand for on-board diagnostics, second generation. Essentially, it is a government-mandated method of plugging into the computer systems of modern cars. An OBD2 port hides under the dash of every car built after January 1st, 1996 that conforms to US regulations.3

To understand why the government came to require OBD2 requires a brief history lesson. In the old days, cars were simple, rudimentary machines with a basic engine and drivetrain. There were no computers, no emissions equipment, and hardly any complex componentry. A simple set of wrenches and a knowing eye could fix and repair just about anything.

After the EPA was formed in the 1970s, cars began modernizing. Emissions equipment became mandatory; computers proliferated.4 An array of wires, hoses, and sensors spawned in engine bays of every type of vehicle.

These new electronic systems necessitated onboard diagnostics, but there was no universally agreed-upon system – automakers used whatever method they thought was best. The first generation of universal diagnostics was mandated in 1990 in response to this.5 OBD2 was the more sophisticated, modernized follow-up, and remains the standard to this day.

How does OBD2 work?

Gloved hand holding a bluetooth universal OBD2 scanner

On-board diagnostics run largely in the background, as invisible as your computer anti-virus software. In-car sensors monitor various emissions parameters, comparing actual readings to specific parameters as defined by the engineers. If a sensor picks up a reading outside of these parameters, it alerts the diagnostic system, which in turn triggers your check engine light.

The precise reason your check engine light turns on is stored in the system as a code. This code can only be retrieved by plugging a tool called a scanner into the OBD2 port. Once plugged in, a scanner can find and display the relevant code. If there are no codes stored, the scanner won’t transmit anything.6

Are OBD2 scanners universal?

As we stated earlier, yes, OBD2 scanners are universal. You can buy any OBD2 scanner and find it will plug into the port tucked under your dashboard. This is true for the cheapest Bluetooth scanners and the priciest full-service diagnostic units. If this has you struggling to find the right code reader for your needs, see our take on the best OBD2 scanners.

However, it’s important to know that some cars may throw codes specific to their manufacturer. These manufacturer-specific fault codes can’t be read by the universal scanners. Special tools and connectors are required to find and diagnose these issues. If a warning light appears on the dash but a standard code reader says nothing is amiss, odds are a manufacturer-specific code has been thrown. Expect to visit your local dealer if you find yourself in this situation.

Can an OBD2 scanner turn off my check engine light?

Yes and no. OBD2 scanners access the car’s computer and memory vault, where the car has stored an astonishing mass of data. This data is more than just fault codes: OBD2 records information on drive cycles, real-time engine parameters, and emissions information. If you’re the nerdy type, you might be interested in reading the governing standard regarding OBD2: SAE standard J1979.

When you go to clear a code with a scanner, you’re actually erasing the memory of the diagnostic system. The stored number of drive cycles is brought back to zero; data on all other parameters is likewise brought back to zero. This lets the car re-learn all emissions and engine data in order to freshly compare it to the parameters and settings originally defined by the manufacturer.

If you properly repair the car before clearing the codes, this is all a non-issue – as the car begins to accumulate data from scratch, all systems will again operate within their designated, allowed operating range. Nothing will be out of the ordinary, and thus no codes will be thrown.

However, if you simply clear a fault code without attempting a repair, it’ll appear again within a certain number of drive cycles. This usually occurs around the 150-200 mile mark. Not coincidentally, this is also the minimum mileage a car should be driven before an emissions test if its OBD2 data was recently reset. Driving that far beforehand is necessary for the car to compile a history of emissions data.

Are all OBD2 scanners the same?

It depends on the scanner. The pricier, more sophisticated models can reset check engine lights and do a host of other functions as well, including accessing engine vitals and other metrics. Modern engines store an astonishing amount of data, and the most advanced scan tools can tap into that wealth of information.

For most car owners, though, it doesn’t make sense to purchase something with that level of functionality – that caliber of scan tool is intended for professional mechanics and engine builders. More modest (and far more affordable) scanners aren’t so capable but will read and clear engine fault codes with the same accuracy as the pricier models.

Parting Thoughts

OBD2 scanners are universal. You can buy any model, alarmingly cheap or astonishingly expensive, and read the generic emissions codes being thrown by your car. However, fancier scanners enable far more than mere code reading, while manufacturer-specific codes require manufacturer-specific tools.

We also have to reiterate that clearing a fault code doesn’t erase the issue that initially triggered the code. If your car’s check engine light appears, be sure to make the proper repairs once you’ve diagnosed the issue. It’s the guaranteed way of turning off your check engine light for good.

Article Sources

Ride Digest uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

  1. Brewer C. How To Use An OBD2 Scanner. Carfax.com. Published July 31, 2020. Accessed July 21, 2021.
  2. L M. What Year Did OBD2 Start? Here’s A Brief History Lesson. Scanneranswers.com. Published January 25, 2020. Accessed July 21, 2021.
  3. Barreto V. What is OBDII? History of on-board diagnostics. Geotab.com. Published November 25, 2020. Accessed July 21, 2021.
  4. Environmental Protection Agency. History of Reducing Air Pollution from Transportation in the United States. Epa.gov. Accessed July 21, 2021.
  5. TransportPolicy.net. US: On Board Diagnostics. Transportpolicy.net. Accessed July 21, 2021.
  6. Samsara. A Guide to Understanding DTC Codes. Samsara.com. Published March 31, 2021. Accessed July 21, 2021.

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