Volkswagen Passat 1995 Official Factory Repair Manual page 1556

Readiness code
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Readiness code
Function
The readiness code is an 8 digit number block
that indicates the results of an emission
relevant On Board Diagnostic (OBD).
When the diagnostic for a system (e.g.:
secondary air system) has run through
successfully, the respective digit of the
number block is set from 1 to 0.
On Board Diagnostics are performed at
regular intervals during normal vehicle
operation. After repairing an exhaust relevant
system, the readiness code should be
generated via a road test to ensure that these
systems are working according to
specifications. If a malfunction is recognized
during diagnostic, it is stored in DTC
memory.
The readiness code is erased every time DTC
memory is erased or when voltage supply is
interrupted. DTC memory should therefore
only be erased when there are DTCs stored.
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