The Readiness Code is a set of 8 bits, each of
which corresponds to one monitored emissions "system" in an OBD-II car. When all
readiness bits show "Passed", it means that all systems have been checked and
the on-board tests.
Whenever you clear DTC's or remove power from the ECU, all readiness bits will
be set to "fail". Most cars do not have all 8 systems, so as soon as you apply
power again, the bits corresponding to systems that are not actually in the car
will come up "Passed" again.
It takes a variety of specific driving
conditions to "test" all the systems. It can be done in a short time using a
very specific and complicated procedure found in the On Board Diagnostic section
of the Factory Repair Manual for your engine. The alternative is just to drive
the car for 2-3 days. Make sure you include at least one short highway
trip, and your Readiness Bits should all read "Pass" again.
Back] to return to the Controller Information Screen.
As of version 409.0 VAG-COM also Decodes Readiness bits into meaningful data
on modern TDI engines (a VAG-COM exclusive, not even the VAS-5051/5052