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What is an OBD port and what are they used for?

Latest car guides

December 28th 2021 info

Cars these days are unrecognisable compared to previous years, both in terms of aesthetics and technical features.

Much like our smartphones, modern cars are equipped with onboard processors that control aspects of the vehicle, from monitoring tyre pressure to controlling gearboxes.

From time to time, though, cars inevitably break down. The exact causes of these breakdowns are sometimes obscure. Thankfully, the motoring industry has developed an innovative approach to solving these sorts of problems with the Onboard Diagnostics (OBD) port.

Find out what the OBD port does, where you can find yours, and how they could potentially get you out of some tricky situations with your car.

What is an OBD II port?

The OBD port is a universal connector that mechanics can use to tap into a vehicle’s computer for running all sorts of tests and diagnostics.

The history of the device goes as far back as 1968, when Volkswagen introduced its first form of on-board computer system. Despite its technical inferiority, this invention made use of capacitors, resistors, and sensors to monitor many aspects of the vehicle like road speed and engine temperature.

Since 1996, every single car is legally required to be equipped with an OBD II port. Before this, manufacturers were free to adopt this technology by any means they wished. This variation introduced significant costs for mechanics who were required to buy different tools  for each manufacturer’s design. This all began to change in 1987, with the introduction of OBD I.


There are two versions of OBD ports: OBD I and OBD II. OBD II is the direct successor to OBD I and introduces some improvements to the first generation of this technology.

While both are used to diagnose car problems, the second generation of this technology is much more popular. With so much jargon being thrown around, you may be wondering: what’s the difference between OBD 1 and OBD 2?

Namely, the main benefits of this second iteration of OBD technology are centred around the accuracy of fault detection. While OBD I was primarily focused on energy consumption and power output, OBD II can universally diagnose more intricate issues with a standardised set of error codes that can be used across multiple vehicles.

This universality is what ultimately made OBD II stand out the most as it offers greater fault detection abilities, and even the ability for one reader to be used across multiple vehicles.

OBD port uses

While the primary intention of the OBD port is focused on vehicle diagnostics, as time has passed, vehicle accessory manufacturers have developed some further uses that go far beyond the needs of mechanics.

Diagnosing engine faults

By using OBD scanners, users can identify potentially detrimental mechanical faults within their vehicles. These faults can range from an engine misfire to pinpointing a faulty sensor.

ECU reprogramming

Thanks to the technical improvements provided by OBD II, a further benefit that OBD brings comes through being able to interact with the vehicles Engine Control Unit (ECU). This allows existing engine configurations to be read and overwritten in pursuit of increased power or economy.

 Read more: What is car remapping and is it legal? The advantages and disadvantages of car remapping.

Vehicle telematics

New drivers sometimes find it difficult to pay for car insurance due to the high prices they face as an inexperienced motorist. However, some insurers may offer new drivers the ability to have a ‘black box’ installed in their vehicle that monitors driving behaviour. This allows insurers to offer lower-priced premiums, albeit while restricting new drivers to a curfew and constrained mileage.

These devices can be attached to OBD ports as an unobtrusive means of tracking a driver’s day-to-day progress.

Where is the OBD port located?

It’s important to know the OBD port location on your car. This can come in handy in case of an engine emergency.

While the exact location of an OBD port varies on a car-by-car basis, they are frequently found within the dashboard alongside the steering column. If you’re unsure, you should consult your vehicle’s manual for further guidance.  

Appearance-wise, the OBD II port is a 16 pin connector that is shaped like a rectangle.

Vehicle guidance from findandfundmycar.com

Now that you know what an OBD port does, you’ll be well on your way to keeping your car up and running for years to come.

Thankfully, buying through findandfundmycar.com means that you won’t have to worry about reliability. All of our dealers are extremely experienced and trustworthy, so you know you’ll be getting a quality car no matter which one you choose.

Have a look through our listings of used cars across the UK today.

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