Toyota Prius HSD 2006, Owner'S Manual

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Some states have vehicle emission in-
spection programs which include OBD
(On − Board Diagnostics) checks.
The OBD system monitors the operation
of the emission control system. When the
OBD system determines that a problem
exists somewhere in the emission control
system, the malfunction indicator lamp
comes on. In this case, your vehicle may
not pass the I/M test and need to be
repaired. Contact your Toyota dealer to
service the vehicle.
Even if the malfunction indicator lamp
does not come on, your vehicle may not
pass the I/M test as readiness codes
have not been set in the OBD system.
Readiness codes are automatically set
during ordinary driving. However, when the
battery is disconnected or run down, the
codes are erased. Also, depending on
your driving habits, the codes may not be
completely set.
Also, if the malfunction indicator lamp had
come on recently due to temporary mal-
function such as a loose fuel tank cap,
your vehicle may not pass the I/M test.
The malfunction indicator lamp will go off
after taking several driving trips, but the
error code in the OBD system will not be
cleared unless about 40 trips or more are
taken.
If your vehicle does not pass the I/M test
and the malfunction indicator lamp does
not come on, contact your Toyota dealer
to prepare the vehicle for re − testing.
Emissions inspection and
maintenance (I/M) programs