The Readiness Staus 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 have passed the
Whenever you clear DTC's or remove power from the ECU, all
readiness bits will be set to "Failed or Incomplete". 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.
to return to the Controller Information Screen.
also Decodes Readiness bits into meaningful data on modern TDI
engines (a Ross-Tech exclusive, not even the
VAS-5051/5052 does this!):
function is only available on Engine Controllers that are
OBD-II compliant (all 1996 and newer US-Model gasoline
models and older TDI's may not support this function even
though they are otherwise OBD-II compliant. OBD-I did not
require any "monitors".
function may not work on 12V 2.8L V6 or 3.7L V8 engines
which have readiness bits stored in or near Measuring
Block Group 029.