In short
- An ELM327 translates between the car's control units and your phone or computer.
- Almost all of those sold today are clones; a genuine "v1.5" never existed.
- iPhone: Wi-Fi or Bluetooth LE (classic Bluetooth will not work). Laptop and FORScan: USB, the most stable link.
An ELM327 is a small adapter that plugs into the car's OBD2 diagnostic port (usually under the steering wheel) and acts as a translator between the vehicle's control units and a phone or computer. With it and an app you can read and clear fault codes, watch live engine data and, with the right adapter and software, even change settings.
Where the name comes from
ELM327 was the name of a microcontroller made by the Canadian company ELM Electronics. Its job is to understand the different OBD2 diagnostic protocols (CAN, ISO 9141-2, KWP2000, J1850…) and give software a simple way to talk to the car using text commands ("AT commands").
ELM Electronics announced in 2020 that it would close the business in 2022. Today almost every adapter sold as an "ELM327" is a clone: a device that imitates the original chip using another microcontroller and copied or rewritten firmware.
What it can (and cannot) do
It can:
- Read and clear engine fault codes (the amber warning light).
- Show live data: rpm, temperatures, lambda sensors, fuel trims, consumption…
- Help you check a car before an inspection or before buying it second-hand.
- With brand-specific software, reach other modules (ABS, airbag, body) and change settings.
It cannot:
- Replace professional equipment for ECU reprogramming: that is a job for workshop tools.
- Reach modules on buses that the adapter cannot access from the OBD2 port (see HS-CAN and MS-CAN below).
- Work on very old cars without OBD2 (in Europe, roughly petrol cars before 2001 and diesels before 2004).
Versions: the "v1.5" and "v2.1" confusion
The original maker only released versions 1.0 to 1.4b and 2.0 to 2.3. There never was a genuine ELM327 v1.5: that number was invented by clone makers.
There never was a genuine ELM327 v1.5.
The version number is just what the firmware replies when an app asks for it (the ATI command): a clone can report any version it likes. What really decides how an ELM327 behaves is the chip and the firmware inside, not the number on the box:
| What to look at | Why it matters |
|---|---|
| The chip | The PIC18F25K80 is the microcontroller in the clones that diagnostic forums rate best: from the same family (PIC18) as the original ELM327, usually running firmware based on 1.4. |
| The firmware | It is what implements (or not) the commands that apps ask for. That is why the same model can behave differently from batch to batch. |
| The advertised version (v1.5, v2.1…) | Only a hint: two adapters with the same label can carry different chips, and one with a PIC18F25K80 can report itself as v1.5 or as v2.1. |
Every generic ELM327 sold by Satkit, the publisher of this guide, uses the PIC18F25K80 chip, both those that report v1.5 (Bluetooth v1.5, USB, Wi-Fi) and those that report v2.1 (Mini v2.1 and v2.1 HH).
How those three Bluetooth adapters really differ (size, price and older cars) is in ELM327 v1.5 vs Mini v2.1 vs v2.1 HH.
Watch out
Since the firmware reports its own version, the best clue is a seller who states the chip and which apps it has been tested with. If you already have the adapter, an app such as ELM327 Identifier (Android) shows which commands it really answers.
Bluetooth, Bluetooth LE, Wi-Fi or USB
Inside they all do the same job; what changes is how they talk to your phone or computer. That decides which devices they work with, so choose it before the version.
| Connection | Works with | Pros and cons | Models in this guide |
|---|---|---|---|
| Classic Bluetooth | Android and Windows. Not iPhone | ✓ The cheapest; the phone keeps its Wi-Fi. ✕ No good for iPhone or iPad | v1.5, Konnwei KW903, Mini v2.1, v2.1 HH |
| Bluetooth LE (4.0) | iPhone, Android and Windows, with apps that support it | ✓ Works with iPhone without taking the Wi-Fi. ✕ Pricier; the app must support it | Vgate vLinker BM+ (BMW and MINI) |
| Wi-Fi | iPhone, Android and Windows | ✓ Works with almost any phone or computer. ✕ Takes over the phone's Wi-Fi: no Wi-Fi internet while in use | ELM327 Wi-Fi, Vgate iCar2 |
| USB | Windows laptop | ✓ The most stable link: the one to use for programming with FORScan. ✕ Computer only, wired | ELM327 USB, ELS27 |
- Classic Bluetooth: used by the cheapest ELM327s. iOS does not let these apps use classic Bluetooth, so an iPhone or iPad will not find it. There are Apple-certified exceptions such as the OBDLink MX+, but they are not cheap ELM327s.
- Bluetooth LE (4.0): the one that works on iPhone without losing Wi-Fi. On iPhone you do not pair it in Settings: the app finds it.
- Wi-Fi: the adapter creates its own network; you join it in the phone's settings and then enter its address and port in the app. A phone can only be on one Wi-Fi network at a time, so while you use it there is no Wi-Fi internet.
- USB: nothing to pair and no signal dropouts. It is the choice for a Windows laptop and the one FORScan recommends for configuring and programming modules, because a dropped connection mid-write can leave a module misconfigured. It does not work with phones.
In short
iPhone? Wi-Fi or Bluetooth LE. Android? Classic Bluetooth. Programming from a laptop? USB. All three, with prices and a verdict, in Bluetooth, Wi-Fi or USB.
Got an iPhone and your ELM327 won't connect? We cover it in detail, with the steps for Wi-Fi and Bluetooth LE and the IP setting iOS 14 or later sometimes needs, in how to connect an ELM327 to an iPhone.
HS-CAN and MS-CAN: why "modified" ELM327s exist
Many cars have more than one CAN network. The high-speed one (HS-CAN) is on pins 6 and 14 of the OBD2 port, which every ELM327 uses. But Ford, Mazda and other makers also have a medium-speed network (MS-CAN) for comfort, instrument cluster, climate or audio modules, which on Ford comes out on different pins (3 and 11).
A standard ELM327 cannot see that network. That is why there are modified adapters with an HS/MS-CAN switch: a small toggle that moves the adapter's lines to the MS-CAN pins. FORScan supports them and asks you to flip the switch when needed.
The more convenient alternative is an adapter that switches networks by itself, such as the ELS27 or the ones FORScan recommends (OBDLink EX over USB). Nothing to touch, and the connection is usually faster and more reliable.
The two USB options for FORScan, side by side: ELS27 vs ELM327 USB.
Do I need it?
If you only want to read engine faults, no: a standard ELM327 is enough. If you own a Ford or Mazda and want to reach every module or enable features, you do need MS-CAN access.
Compatible apps
- Torque Pro (Android): very popular for live data with custom dashboards and for reading faults.
- Car Scanner ELM OBD2 (Android and iPhone): free with optional purchases, with extra features for some brands. On iPhone you need a Wi-Fi or Bluetooth LE adapter.
- FORScan (Windows, plus FORScan Lite for Android and iPhone): the reference tool for Ford, Mazda, Lincoln and Mercury, and only for those brands.
We go through them one by one, with prices, the adapter each one needs and the steps to read and clear fault codes, in our guide to ELM327 apps. And if you ride, see which apps work on motorcycles: with the right cable, an ELM327 works on many of them too.
Which one to choose
- Getting started on Android: an ELM327 Bluetooth v1.5 or, if you want a brand, the Konnwei KW903.
- For iPhone: a Wi-Fi one, such as the ELM327 Wi-Fi or the Vgate iCar2, or a Bluetooth LE one.
- For a Windows laptop: the ELM327 USB.
- Ford or Mazda with FORScan on a laptop: a USB adapter with MS-CAN access, preferably with automatic switching (ELS27) rather than a manual toggle.
- BMW or MINI with BimmerCode or BimmerLink: the Vgate vLinker BM+. It is Bluetooth 4.0, so it also works with iPhone.
- For a motorcycle: it depends on the make and year; you almost always need an adapter cable for the bike's socket. ELM327 for motorcycles explains what works with each make.
- Torn between two models? We compare them one to one, with a verdict for your case, in the comparisons.
Before you program
Before changing any setting, always back up the module configuration from within the software and keep the car battery charged.
Products mentioned
ELM327 Bluetooth OBD2 v1.5
Bluetooth OBD2 adapter to read and clear fault codes and see live engine data on an Android phone or a PC.
Where to buyfrom €8.60
Prices incl. VAT checked on 7 October 2026; they may change.
ELM327 Wi-Fi OBD2
Wi-Fi OBD2 adapter that creates its own network: works with iPhone, Android and Windows PCs. Reads and clears engine fault codes and shows live data.
Where to buyfrom €17.22
Prices incl. VAT checked on 7 October 2026; they may change.
ELM327 USB v1.5
USB OBD2 cable for a Windows laptop: the most stable way to read and clear fault codes and see engine data on a computer.
Where to buyfrom €11.08
Prices incl. VAT checked on 7 October 2026; they may change.
ELS27 USB for FORScan
USB adapter built for FORScan: reaches the HS-CAN and MS-CAN buses on Ford and Mazda with no manual switch.
Where to buyfrom €14.39
Prices incl. VAT checked on 7 October 2026; they may change.
Vgate vLinker BM+
Vgate Bluetooth 4.0 adapter for BMW and MINI with BimmerCode and BimmerLink. iPhone, Android and Windows.
Where to buyfrom €47.97
Prices incl. VAT checked on 7 October 2026; they may change.
Sources
- ELM327 — Wikipedia
- FORScan: supported adapters and vehicles
- FORScan forum: MS-CAN access with a modified ELM327
- Car Scanner: choosing an OBD2 adapter
- Car Scanner: configuring a Bluetooth 4.0 (LE) connection on iPhone/iPad
- Car Scanner: iOS Wi-Fi connection troubleshooting
- OBD Auto Doctor: supported adapters by platform
- BimmerCode: supported adapters
