Codes p0171 and p0174
Senior Member
Joined: Dec 2006
Posts: 43,539
Likes: 818
From: Joplin MO
Those are lean codes, usually caused by unmetered air entering the intake - i.e. a vacuum leak. Gas cap has nothing to do with this. Check the PCV system and the intake tube between the MAF and the throttle body.
Senior Member
Joined: Jul 2007
Posts: 244
Likes: 0
From: Ft Worth, TX
My manual says this about it, but it never takes that long when I clear them and am expecting/waiting for some to come back that I know are present:
"
"
Preparing your vehicle for
inspection/maintenance testing
In some localities it may become a
legal requirement to pass an
Inspection/Maintenance test of the
on-board diagnostic (OBDII)
system. If the vehicle’s powertrain
system or battery has just been
serviced, the OBD II system is
reset to a “not ready for I/M
testing condition.” To ready the
OBD II system for I/M testing, the
law specifies that additional mixed
city and highway driving is
necessary to complete the check of
the OBD II system.
The driving modes required to
reach the ready condition consist
of a minimum of 30 minutes of city
and highway driving as described
below:
Maintenance and care
196
² 20 minutes of driving in stop
and go city-type traffic with at
least four idle periods.
² 10 minutes of driving on an
expressway or highway.
Before completing the above
driving modes, the engine must be
warmed up and at operating
temperature. Once started, the
vehicle must not be turned off
during the above driving modes.
Maintenance and care
197
"
inspection/maintenance testing
In some localities it may become a
legal requirement to pass an
Inspection/Maintenance test of the
on-board diagnostic (OBDII)
system. If the vehicle’s powertrain
system or battery has just been
serviced, the OBD II system is
reset to a “not ready for I/M
testing condition.” To ready the
OBD II system for I/M testing, the
law specifies that additional mixed
city and highway driving is
necessary to complete the check of
the OBD II system.
The driving modes required to
reach the ready condition consist
of a minimum of 30 minutes of city
and highway driving as described
below:
Maintenance and care
196
² 20 minutes of driving in stop
and go city-type traffic with at
least four idle periods.
² 10 minutes of driving on an
expressway or highway.
Before completing the above
driving modes, the engine must be
warmed up and at operating
temperature. Once started, the
vehicle must not be turned off
during the above driving modes.
Maintenance and care
197
