ELM327 v1.4b

OBD to RS232 Interpreter – firmware version 1.4b
This older product has been discontinued.

This product is currently out of stock and unavailable.


Almost all of the automobiles produced today are required, by law, to provide an interface for the connection of diagnostic test equipment. The data transfer on these interfaces follow several standards, but none of them are directly usable by PCs or smart devices. The ELM327 is designed to act as a bridge between these On-Board Diagnostics (OBD) ports and a standard serial interface.

In addition to being able to automatically detect and interpret nine OBD protocols, the ELM327 also provides support for high speed communications, a low power sleep mode, and the J1939 truck and bus standard. It is also completely customizable, should you wish to alter it to more closely suit your needs.

The data sheet discusses all of the ELM327’s features in detail, how to use it and configure it, as well as providing some background information on the protocols that are supported. There are also schematic diagrams and tips to help you to interface to microprocessors, construct a basic scan tool, and to reduce power consumption.

If you are wondering what the differences are between the many ELM327 versions, you may find the Version History section in Help / OBD / Tips to be helpful.


  • Diagnostic trouble code readers
  • Automotive scan tools
  • Teaching aids


  • Power Control with standby mode
  • RS232 baud rates to 500 kbps
  • Automatically searches for protocols
  • Fully configurable with AT commands
  • Low power CMOS design

Connection Diagram

( PDIP or SOIC, top view )
ELM327 v1.4b connection diagram

Block Diagram

ELM327 v1.4b block diagram


The ELM327 v1.4b data sheet (373K):

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The ELM327 v1.4b data sheet iBook (11MB):


Alternative Products

The following offer more alternative versions of the ELM327 firmware:

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