Professional_Tool_And_Equipment_News_August_2019 - 40

p Part of Launch Tech's Roxie detailed pre- or post-scan report, which can be emailed to the
service adviser and/or the customer.

p When performing pre and post scans, observe the monitor status in order to
determine if all monitors are complete.

also need to make sure the system that
had a problem was not preventing a different system from monitoring its condition. This could create a situation where a
check engine light could illuminate if the
now able-to-run system monitor detects
a fault. This becomes abundantly clear in
the following case study.

CASE STUDY: 2002 FORD F-250,
6.8L V10 GASOLINE ENGINE

This vehicle came in with the CEL illuminated and an obvious misfire present.
The initial scan showed a P0303 (misfire
on cylinder number 3) code and a P1000
(all monitors have not been completed
since last clearing) code. No additional
codes were present in other systems,
there were no pending codes, and the

PTEN

AUGUST 2019

evaporative emissions control (EVAP)
and heated oxygen sensor (HO2S) monitors were incomplete.
Since a P1000 code was present and
an EVAP monitor is typically one of the
last to run, we did not concentrate on the
EVAP system at that time. The fact that
the HO2S monitor had not completed
led us to look further into what could
stop that particular monitor from running, especially due to the fact that having either incomplete or incorrect data
from oxygen sensors can directly affect
cylinder operation.
We went to Mitchell 1 and found that
in order for the EVAP monitor to run,
it required the HO2S monitor to complete and pass its system test beforehand.
Additionally, the HO2S monitor is not

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able to run if there are any misfire codes
present. With this information, our concentration shifted to the cause of the misfire, with the assumption that once it was
repaired, all of the monitors could run.
While inspecting the ignition components, we found an obviously corroded connector on the ignition coil for
cylinder 3. All other coils showed small
amounts of corrosion on the boots, and
the spark plugs showed extended gaps.
We suggested to the customer that we
replace the one ignition coil, all the
spark plugs, and all the coil boots. These
repairs corrected the misfire. We cleared
the fault codes and performed a drive
cycle. A post-scan revealed a P1000 code.
Looking at the monitors, we found
that the HO2S monitor had now completed, but the EVAP system had not yet
completed. We returned the vehicle to
the customer; we asked them to drive the
vehicle for a few days and to return to the
shop so that we could see whether or not
there were issues with the EVAP system
once the monitor was completed.
This is where it gets interesting. When
the vehicle returned, we connected our
scan tool to the vehicle and found a
P1000 code. The vehicle had been driven
about 75 miles over the course of a few
days, so all monitors should have been
completed. We then checked the monitor
status and found none of the monitors
were completed.
We had scanned the truck after our
original repair and road test and had
confirmed that all the monitors had run,
except the EVAP system. We asked the
customer if the battery had either been
disconnected or jump-started. Either
situation could have caused the system
to clear codes requiring monitors to be
re-run. They said they had no battery
issues. Our next step was to perform
another drive cycle to see if the monitors would run.
After a twenty minute test drive, we
connected the scan tool and again saw a
P1000 code and that all monitors were
complete except the EVAP system.
In order to make sure there was
nothing that could cause the computer
memory to clear, I asked the customer

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Professional_Tool_And_Equipment_News_August_2019

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