Specifications

16 of 19ELM323DSD Elm Electronics – Circuits for the Hobbyist
< http://www.elmelectronics.com/ >
Quick Guide for Reading Trouble Codes
If you don’t use your ELM323 for some time, this
entire data sheet may seem like quite a bit to review if
your ‘Check Engine’ light does eventually come on.
The following provides a quick procedure which may
prove helpful in that case (note that the ‘>’ is the
ELM323’s prompt character):
ELM323
Connect using HyperTerminal, ZTerm, etc.,
9600 8N1, and no handshaking
Ignition Key to ON, but vehicle not running
>ATZ
to be sure the IC is reset and responding
>0100
to be sure the car is responding
>0101
to see how many codes are present
(look at the second digit of the 3rd byte)
>03
to see the codes
Ignore the first byte and read the others in
pairs. The table on page 12 helps.
>04
to reset the codes
FIX THE VEHICLE!