Roadi RDT40 - Manual (Page 5)

OWNER S MANUAL
,
OBD2 CODE READER
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accurately find and fix the problem. Here below follow three pieces of
such crucial information:
Whether the Malfunction Indicator Lig ht (MIL) is commanded 'on' or
'off';
Which, if any, Diagnostic Trouble Codes (DTCs) are stored;
Readiness Monitor status.
2.2 Diagnostic Trouble Codes (DTCs)
OBDII Diagnostic Trouble Codes are stored by the on-board computer
diagnostic system in response to a problem found in the vehicle. These
codes identify a particular problem area and are intended to provide you
with a guide as to where a fault mig ht be occurring within a vehicle. OBDII
Diagnostic Trouble Codes consist of a five-digit alphanumeric code. The
first character, a letter, identifies which control system sets the code. The
other four characters, all numbers, provide additional information on where
the DTC originated and the operating conditions that caused it to set. Here
below is an example to illustrate the structure of the digits: