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Figure 4-15 Sample DTC & FFD Screen
Stored Codes
Stored codes are the current emission-related DTCs from the ECM of the
vehicle. OBD II/EOBD Codes have a priority according to their emission
severity, with higher priority codes overwriting lower priority codes. The
priority of the code determines the illumination of the MIL and the codes
erase procedure. Manufacturers rank codes differently, so expect to see
differences between makes.
Pending Codes
These are codes that were generated during the last drive cycle, but before
the DTC actually sets, two or more consecutive drive cycles are needed.
The intended use of this service is to assist the service technician after a
vehicle repair and after clearing diagnostic information, by reporting test
results after a driving cycle.
a) If a test failed during the driving cycle, the DTC associated with that
test 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 by this service do not necessarily indicate a
faulty component or system. If test results indicate another failure
after additional driving, then a DTC is set to indicate a faulty
component or system, and the MIL is illuminated.
Freeze Frame
Typically, the stored frame is the last DTC that occurred. Certain DTCs that
have a greater impact on vehicle emission, have a higher priority. In these
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