User Manual

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Figure 4-29 Sample DTC & FFD Screen
 Current Codes
Current codes are emission-related DTCs from the ECU of the vehicle. OBD
II/EOBD Codes have a priority according to their emission severity, with higher-
priority codes overwriting lower-priority ones. The priority of the code determines the
illumination of the Malfunction Indicator Light (MIL) and the codes erase procedure.
Manufacturers rank codes differently so expect display to vary by vehicle.
 Pending Codes
These are codes whose storing conditions have been met during the last drive cycle,
but need to be met on two or more consecutive drive cycles before the DTC is stored.
The purpose of displaying pending codes is to assist the service technician after a
vehicle repair when diagnostic information is cleared, by reporting test results after
a single driving cycle.
a) If a test fails during the driving cycle, the DTC associated is reported. If the
pending fault does not occur again within 40 to 80 warm-up cycles, the fault is
automatically cleared from memory.
b) Test results reported do not necessarily indicate a faulty component or system.
If test results indicate another failure after additional driving, a DTC is stored to
indicate a faulty component or system.
 Freeze Frame
In most cases the stored frame is the last DTC reported. Certain DTCs, those that
have a greater impact on vehicle emission, have a higher priority. In these cases,
DTC of the highest priority is the one for which the freeze frame records are retained.
Freeze frame data includes a “snapshot” of critical parameter values at the time the