Best OBD readers 2023

The ominous glow of a warning light is enough to ruin any driver’s day. A puncture, blown bulb or empty washer bottle will be a simple fix, but an engine warning light is a great unknown. The only way to check what has gone wrong is to interrogate the car’s electronic brain.

A garage will charge for this diagnosis, but it is easy to check yourself using an On Board Diagnostics (OBD) reader, which simply plugs into a standardised socket present in almost every car made over the past 25 years.

Here, we’re testing products at the DIY end of the market. These have some limitations and can’t usually check codes for safety systems, but they could pay for themselves, even if you only use them once to check an engine fault.

Most will also let you see the VIN etched into the car’s electronics so it can be cross-checked with the paperwork on a vehicle you are thinking of buying.

Wireless readers are smaller and generally cheaper, but need a connection to a smartphone or tablet. Wired readers are more convenient, easier to use with gloves and grimy hands, but usually provide less information. We tested both.

We plugged the readers into a selection of cars of different ages, including a 2008 Mazda 2 and 2014 Peugeot 208 with known faults that were generating a warning light. Wireless readers were connected via Bluetooth to an iPhone using the app suggested by the device’s instructions.

All of the devices here will read and clear engine fault codes. The more sophisticated devices will be able to tell you much more about the vital statistics of your car and check the VIN etched into the electronic brain – which will help spot a cloned model.

For just an occasional check, even the cheapest will do the trick – but it won’t be as convenient or easy to use. At under £14, the Scanex is hardly a huge investment, though, if you don’t mind connecting by Bluetooth. If you use a scanner more often and don’t want a wireless connection, the Topdon is a cut above the others.

Bluetooth readers can be left attached to the port while you are driving, allowing you to monitor readings from the engine and gearbox. The Scanex makes it easy to do this, because it is smaller than the other devices here and less likely to get in the way if your port is located in a footwell.

The device also includes an automatic off function to avoid draining the battery if left in place. Scanex’s suggested app – KonnweiLink OBD Check – is no longer supported, but the unit connected easily to alternatives suggested by its rivals and worked well.

Compared with the others, the Topdon is a bit pricey, but if you’ll use an OBD tool frequently, it will make the job much easier. The cable is a huge 130cm long, so you don’t need to kneel while using it, and there is an LED in the plug to illuminate the OBD port.

Once connected, the information is displayed on a 2.4-inch colour screen. It tells you the code number and gives details, including manufacturer-specific codes, unlike other wired readers here. It made its rivals look old-fashioned.

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The wired winner from our last test continues to impress – and the price has dropped by £4 since, so it’s even better value. With six buttons, it’s quicker to navigate these menus than rivals with two, and the large display lets you view more information at once.

We liked the shortcut buttons to view codes and check a car’s VIN without using the menus. The 76cm-long cable also meant we weren’t stooping in the footwell or leaning across the seats on cars with awkward OBD port locations.

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Aldi’s wired reader is one of the cheapest ways we could find of reading and clearing codes – so cheap, in fact, that you could buy it even if you don’t have an immediate need for it. There are some obvious signs of where the cost has been trimmed, with a two-button operation and a basic LCD screen, which makes reading and clearing codes as tricky as changing the clock on your oven.

The cable is the shortest here too, so you’ll be kneeling in the footwell of most cars while prodding the buttons.On the plus side, the instruction book is unusually comprehensive and includes a list of common fault codes. This Aldi unit does the job at a tempting price.

This unbranded scanner was the cheapest we could find on Amazon that supported both Apple iOS and Android connections. The suggested app – Faslink – gave an instant connection and was surprisingly comprehensive. However, the Bluetooth did drop occasionally and crash the app. It was also tricky to see the LED indicators on some cars because they were on the side facing away from us rather than on the end.

Another problem is the size: it may be too large to fit in a footwell of a car while driving and couldn’t be used on our Land Rover. As a result, we’d pay the extra pound for the smaller Scanex.

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Although it looks different, the screen on the Streetwize works in a very similar way to the Foseal’s, which lifts it up a notch in terms of clarity from the cheaper Auto XS. It also had no trouble reading any of our cars and clearing the codes.

But unlike the Foseal, it only has two buttons, so you’ll spend longer scrolling to get through the menus. It only takes a few more seconds, but might become an irritation if you are using it regularly. The short cable means you could also find yourself crouched down in a footwell, which might be forgivable if it were cheaper than its rivals.

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Unlike the other wireless readers, the Streetwize uses a WiFi connection rather than Bluetooth. This seems to involve a far more convoluted process to connect to our iPhone than with its rivals, insisting we disconnected from other WiFi sources first – including the vehicle’s Apple CarPlay.

After waiting several minutes, we were briefly successful in getting a connection and were able to view some live data before it dropped out. We tried it on another app, but had even less success. On the plus side, it’s compact, but there are no indicator lights to tell you it is working and it seems expensive compared with the Bluetooth rivals.

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