OBD2 adapters: clones, good ones and which to buy

Why the adapter matters so much

The adapter is a translator: it takes the phone’s questions over Bluetooth or wifi, passes them to the car through the OBD socket and does the same with the answers. The app can be very good, but if the translator swallows words, gets things wrong or goes quiet, what you see is slow, patchy or missing. Most complaints along the lines of "this app can’t read my car" are really about the adapter.

ELM327: the original and the clones

ELM327 is the name of a chip designed by a Canadian company, Elm Electronics, to do exactly that translation. It worked so well that its way of talking, the AT commands, became the common language of nearly every adapter and nearly every app. Today, "ELM327" on a box nearly always means "ELM327 compatible", not that it has the original chip inside.

Clones are cheap copies. Inside there’s a generic microcontroller, often a PIC of dubious origin or relabelled, running a copy, frequently cut down, of the ELM327 firmware. Some are quite well made; others only know just enough to read a handful of engine values.

The versions that give a copy away

• v1.5. It never existed on the original chip: Elm went straight from 1.4b to 2.0. Any adapter that says ELM327 v1.5 is a clone. That said, some v1.5 units with a good PIC inside are among the cheap ones that work best.
• v2.1. It did exist on the original, but the vast majority of cheap adapters labelled v2.1 are copies, and many of them are the worst: they boast a high version number and can’t do what that version should.
• A higher version, like 2.2 or 2.3, doesn’t guarantee anything on its own either: anyone can write that number.

Where clones fail

• They drop frames. Long answers (the VIN, a list of faults, the data from a control unit) arrive split into several messages in a row. A slow clone can’t keep up, loses one and the answer arrives incomplete or not at all.
• They can’t handle several readings per request. Over OBD you can ask for up to six values at once. Many clones choke and force the app to ask one at a time, so the gauges move in jumps.
• They’re missing commands. To talk to control units other than the engine you have to change the address of the messages, and many cars need a long address that clones don’t understand, or only half understand. The result: control units missing from the scan.
• They struggle on the K-line. Cars from before roughly 2008 talk over the K-line, which has its own greeting to get started and very strict timings. Many clones don’t respect them and never even connect.
• They freeze. They stop answering halfway, disconnect, or have to be unplugged and plugged back in before they respond.
• They drain the battery. Many never switch off. Leave the car parked for a week with the adapter in and you may find a flat battery.

Clearing faults requires stable communication. An adapter that drops messages can leave the operation incomplete. Check the result shown by the app.

How to tell if yours is a clone

• It has no brand, or it’s called OBDII, OBD2, Mini ELM327 or something similar, and the pairing code is 1234 or 0000.
• It claims to be ELM327 v1.5 or v2.1.
• It cost very little. There’s no good adapter for the price of a coffee.
• The real test is using it: Final OBD asks it who it is when it connects, tells you whether it has a professional chip or is ELM327 compatible, and measures how many readings per second it gets from your car.

The ones we recommend

A good reader isn’t the most expensive one: it’s the one that drops no messages, understands every command and answers quickly. We recommend two, equally: the vLinker MS, which is Apple certified and the fastest we’ve measured, and the vLinker MC+, with Bluetooth 4.0. Both understand every command the app uses to talk to each brand’s control units and work on Android and on iPhone.

If you want the best and you have Android, the OBDLink MX+ is the most complete: a professional chip, an encrypted connection and free updates. It uses classic Bluetooth, so for now it doesn’t work with Final OBD on iPhone. And if you’re after something cheaper, the Veepeak OBDCheck BLE+ has both classic Bluetooth and Bluetooth Low Energy, and it also works on both.

Final OBD measures the reader every time it connects, so there’s no need to trust the box. Up to 19 October 2026 we have received 2,745 connection logs, and in 1,631 sessions a car was connected and the reader was measured, from 251 installations of the app.

What our testers’ cars measure

Final OBD measures every adapter when it connects, so you don’t have to trust the box. This is what the first 400 adapters that connected measured, up to 30 September 2026, in their cars and with their phones. Speed is the median number of readings per second; the more, the smoother the gauges and the faster the control units are read.

The difference is big: a good adapter brings five to ten times more readings per second than a cheap clone. We still have too few connections from OBDLink adapters, with their own chip, to put them in the table, but they work very well in our test cars. The table will keep updating with what the cars measure.

Classic Bluetooth, BLE or wifi

• Classic Bluetooth. The traditional kind: you pair it in the phone’s settings. It works very well on Android. On iPhone it doesn’t work, except for Apple certified (MFi) adapters.
• BLE, Bluetooth Low Energy (4.0 or later). You don’t pair it in the settings: the app finds it and connects. It works on Android and iPhone. If you have an iPhone, or might switch to one, it’s the safe choice.
• Wifi. The adapter creates its own network and the phone joins it. It works on Android and iPhone, but while you’re on its network the phone usually has no internet, and many cheap wifi adapters are just as much clones as the Bluetooth ones.
• USB cable. That’s for a computer. It isn’t used with a phone.

Check the box carefully before buying: if you have an iPhone, you want to see "Bluetooth 4.0", "BLE" or "iPhone compatible". Some adapters have both radios, classic and BLE, and show up twice in the list with the same name; Final OBD merges them and tries whichever one connects.

What to buy for what you’ll do

• Watching gauges and reading engine faults now and then: a decent clone will do, ideally one of the v1.5 units that work well. If you already have one, try it before buying another.
• Checking a used car before you buy it, going to an inspection with peace of mind or reading every control unit: one of the two vLinker, the MS or the MC+. This is where a clone leaves control units unread.
• A pre-2008 car that talks over the K-line: a reliable reader like the vLinker MS or MC+, which also talk over the K-line. It’s where clones cause the most trouble.
• The most complete, if you have Android: the OBDLink MX+.
• iPhone: the vLinker MS, which is Apple certified, the vLinker MC+, with Bluetooth 4.0, or the Veepeak OBDCheck BLE+, which has BLE. Not the OBDLink MX+, for now. If you buy another one, make it BLE, wifi or Apple certified.

We don’t list prices because they change every month, but the difference between an unbranded clone and a good reader is small compared with what a trip to the garage costs.

What your car gets is in the list of compatible cars.

How Final OBD adapts to your adapter

Every time you connect, Final OBD measures how many readings per second your adapter gets from your car, whether it drops messages and whether it’s missing any commands, and sums it up in one of four levels shown in the menu with bars, like the signal on your phone:

If the adapter drops frames, won’t accept several readings per request or is missing a command, the level goes down even if it’s fast, because what counts is that nothing gets lost. And the app adapts to it: it asks for fewer readings at a time, waits longer between messages, breaks up the commands it doesn’t fully understand and remembers all of that for next time with that adapter. If you know better than the measurement, you can set the level by hand.

With a slow adapter nothing stops working: dashboards move in jumps and long reads take longer. What you won’t see is the app blaming your car for what the adapter is doing.

Three tips

• To read faults you only need the ignition on; there’s no need to start the engine.
• If an adapter won’t connect, switch the ignition off, unplug it for ten seconds and start again before deciding it’s faulty.
• Unplug it if the car is going to sit for several days.

Where the socket is and what each pin does is in the OBD2 connector guide, and the languages each car speaks are in the protocols guide. If something doesn’t add up with your adapter, write to us at info@finalobd.com.