Note:
Version A and B are same inside, different on the cover.
There are several options in the link, please choose the right device, according to your phone android or IOS.
Bluetooth elm327 supports android system only, does not support IOS system, so if you have a iphone, please buy ELM327.
Elm327 supports both android and IOS system.
 
ELM327 interface is able to detect and interpret obd2 / eobd protocols automatically. It also provides support for high speed communications and a low power sleep mode. It use AT commands to communicate with a host device (PC, notebook, for iOS). There are plenty of software packages available, which are fully compatible with this tool. Some of them have pretty useful features, such as engine running parameters monitoring, DTC reading and clearing, MPG meter, etc. You can even write your own software on a specified hardware platform if you wish, because the AT commands are fully documented and very well explained. This tool is only 2.7 x 1.25x 0.9 inches, and it comes with a 6 ft OBDII cable for easy installation. It also includes a power switch built-in to prevent the need for having to constantly disconnect your unit from the OBDII port. It is compatible with 1996 and later vehicles which are obd2 or eobd compliant. Connecting to your iPhone / iPod touch is made by WIFI connection in adHoc mode.
 
Features:
Firmware Version V1.5 (Supports more protocols SAE J1850 than V2.1).
With chip:PIC18F25K80  ,supports all elm327 fucntions,in program ELM327 identifier,it shows full functions.
It understand commands such as  ATPPS and other.
The frequency of the crystal oscillator is 4mHz.

Main Functions:
With proper software installed in the host device, you may have following parameters read out from your vehicle:
Vehicle Speed
RPM
Fuel Consumption
Engine Coolant Temp
Fuel Pressure
Calculated Engine Load
Throttle Position
Intake Manifold Pressure
Air Intake Temp
Timing Advance
Mass Air Flow
Fuel Level
Barometric Pressure
EVAP System Vapor Pressure
Fuel Trim

Note:
Your vehicle may not support all above parameters.How many parameters you can get is depended on the vehicle manufacturer’s implementation.
 
Support Protocols:
1.SAE J1850 PWM(41.6Kbaud)
2.SAE J1850 VPW(10.4Kbaud)
3.ISO9141-2(5 baud init,10.4Kbaud)
4.ISO14230-4 KWP(5 baud init,10.4 Kbaud)
5.ISO14230-4 KWP(fast init,10.4 Kbaud)
6.ISO15765-4 CAN(11bit ID,500 Kbaud)
7.ISO15765-4 CAN(29bit ID,500 Kbaud)
8.ISO15765-4 CAN(11bit ID,250 Kbaud)
9.ISO15765-4 CAN(29bit ID,250 Kbaud)
A.SAE J1939 CAN(29bit ID,250*Kbaud)
B.USER1 CAN(11*bit ID,125*Kbaud)
C.USER2 CAN(11*bit ID,50*kbaud)
Default settings(user adjustable)

Supported cars:
If your vehicle does not fall into any of the above categories, look under the hood and try to locate a label that explicitly states that the vehicle was designed to comply with OBD-2 legislation.
 
This elm327 usually can work on most new car with OBD 16pin Aadapter and 12V engine:
For USA Car brand,after 1996;
For Europe Car brand(petrol),after 2001;
For Europe Car brand(diesel),after 2004;
For Japan Car brand,after 2002;
For Korea Car brand,after 2010;
For Chinese Car brand,after 2009;
For Indian Car brand,after 2010;
For Russian Car brand,after 2012;

Software Requirements:
All ELM327 based software.
IOS system software in Apple store: Car Scanner / OBD Auto Doctor / OBD Car Doctor / EOBD Faciles / Rev / FUZZYCar/ DashComand / SpeedPORT / Nova Scan ...
Attention:For iOS base software are not included you must buy from Apple App Store!
Android system software：Torque pro / Mini OBD2 / OBD Car Doctor / DashComand ...
Windows system: Scanmaster- ELM / PCMSCAN...

Packing list:
1 x ELM327 obd interface