ELM322
Quick Guide for Reading Trouble Codes
If you don’t use your ELM322 for some time, this
data sheet may seem like quite a bit to review when
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
ELM322’s prompt character):
Connect using HyperTerminal, ZTerm, etc.,
9600 8N1, and no handshaking
Key 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 10 helps.
FIX THE VEHICLE!
>04
to reset the codes
ELM322DSE
Elm Electronics – Circuits for the Hobbyist
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