OBD II - E

OBD II - E
Ohio E ✔Check
Can I check if my vehicle’s
monitors are “ready”?
• Drive the vehicle for approximately one week under normal
driving conditions including highway and city driving.
The newer the vehicle the less time it should take.
If for some reason the check engine light is turned off by
disconnecting the battery or the technician cleared the
codes, the following may be helpful to determine whether
your monitors are reading ready and the vehicle is ready for a
retest. Some vehicle owner’s manuals provide information on
how a vehicle owner can determine if the OBD system is ready
for emissions checking by performing a certain procedure.
Visit www.ohioecheck.org for detailed procedures from Ford/
Lincoln/Mercury, Jeep/Chrysler/Dodge, and Honda/Acura
owner’s manuals.
• Check your vehicle’s owner’s manual, contact your local
dealership or visit www.ohioecheck.org for information on
drive cycles.
Based on these owner’s manuals, to check for readiness, turn
the ignition switch to the ON position, but do not crank or
start the engine. The check engine light may light solidly then
either turn off, remain illuminated or blink multiple times. If
the check engine light blinks multiple times, the readiness
codes are not likely set. If the light stays on or turns off, the
readiness codes are likely set. Note that when the engine is
started, the check engine light should turn off unless there are
emissions control problems.
How can I get my vehicle’s
monitors to become “ready”?
If your vehicle has recently been repaired or the battery was
recently replaced or disconnected, the vehicle’s monitors are
not likely ready. Ask your technician if they can make sure that
your vehicle’s monitors are ready before bringing the vehicle
to E ✔Check. The technician may be able to complete the drive
cycle to ensure the monitors are ready. Note, the mechanic
may charge an additional fee for this service.
OBD II
THE ON-BOARD DIAGNOSTICS
VEHICLE EMISSIONS TEST
Failing to complete the drive cycle can cause the vehicle
to be rejected during the retest if monitors are not set to
ready. If the monitors are not ready, they have not run their
diagnostic check of the vehicle’s system and the OBD test
cannot be completed.
The E ✔Check OBD Test Process:
1. The vehicle’s engine will be turned off and an inspector
will attach test equipment to the vehicle’s OBD diagnostic
connector.
2. The inspector will turn the key to illuminate the dashboard
lights to verify the MIL works and does not remain on while
the vehicle is running.
3. The test equipment will attempt to communicate with your
vehicle and look for emission-related DTC that are stored
in the vehicle’s computer memory and check the vehicle’s
monitor status.
4. The engine will be shut off and OBD connector will
be unplugged.
5. The driver receives the vehicle’s test results.
The OBD II hand-held
reader device plugs
directly into a vehicle’s
on-board computer to
Automobile manufacturers have various strategies for
readying the vehicle’s monitors. For this reason, we cannot
give you a simple list of instructions. Drive cycles are a
combination of highway driving, stop and go driving, idling,
and for some vehicles an overnight cool-down period.
quickly check the status
of the emissions system.
In most cases it is possible for the vehicle owner to complete
the drive cycle.
For more information, scan this QR code with your smartphone
to visit our website. Our new website provides details on the
specific type of tests that are performed at each location along
with driving directions from your current location.
FOR MORE INFORMATION:
1.800.CAR.TEST
Continued on back
REV. 8-7-2012
www.ohioecheck.org
www.ohioecheck.info
Understanding on-board
diagnostics
How does the driver know there is
a problem?
What do monitors have to do
with OBD?
Though modern vehicles are getting cleaner due to newer
computer engine management technology and emission
control components, motor vehicles are still the largest
source of toxic and smog-forming air pollution in Ohio.
Despite enhancements to motor vehicles, emissions are
only low when the emission control systems are working
properly. When the engine is not running as efficiently
as possible, performance is lost, fuel is wasted and air
emissions increase.
When the OBD system determines that a problem exists,
a corresponding “Diagnostic Trouble Code” (DTC) is stored
in the computer memory. This DTC or fault code generally
indicates which system or engine component might be
causing the problem. However, at times the code may be a
result of a secondary issue affecting that code so additional
diagnosis by the technician will generally be needed to
isolate the exact problem and identify the proper repair.
If the OBD system detects a problem that may cause the
vehicle’s emissions to exceed one and a half times their
original federal standards, the Malfunction Indicator Lamp
(MIL) is illuminated.
The OBD system is made up of monitors. An OBD monitor
is a computer test or series of computer tests used to
determine operational status of an emission control device
or system. Most vehicles have 5 to 7 monitors but some have
up to 11. When certain criteria are met, the monitors are
activated to test their respective emission control device or
system and thus be ready to deliver information. The vehicle
performs the self-diagnostic computer test when the vehicle
is driven. The monitor will detect when an emission control
device or system has failed and then the check engine light
will turn on.
What is OBD?
On-board diagnostic (OBD) computer systems were
developed by vehicle manufacturers and the federal
government to help technicians diagnose and service
the computerized engine management systems of
modern vehicles. The federal Clean Air Act Amendments
of 1990 required that all 1996 and newer vehicles use
a more advanced OBD system. This second computer
generation OBD or OBD II, monitors vehicle conditions and
components that are related to vehicle emissions. OBD can
detect a malfunction or deterioration of certain engine
components and power train systems before the driver
realizes there is a problem. This sophisticated system serves
as an advanced warning of potential engine damage and
increased air pollution emissions.
What are the typical reasons for
the vehicle’s OBD to fail E ✔Check?
Your vehicle will fail the OBD E ✔Check for the
following reasons:
•The Malfunction Indicator Lamp (MIL) is illuminated
while the vehicle’s engine is running.
•The MIL does not illuminate with the key on and engine
off. This can indicate either a failed OBD system or a
burned out light bulb.
•The OBD diagnostic connector is damaged, missing
or inaccessible.
The MIL is a dashboard light indicating “Check Engine” or
“Service Engine Soon” that informs the driver that a problem
has been detected and vehicle service is needed. By law,
this dashboard light can only be used to indicate an actual
emissions problem. It cannot be used, for example, as a
reminder for regularly scheduled maintenance (this task is
done by other indicator lights).
At a repair shop, a service technician can retrieve the stored
DTC from the computer memory using a computer “Scan
Tool”. By using this information, the technician can diagnose
the problem and make the proper repair.
Are emissions-related repairs
covered by a warranty?
Federal law requires that the emission control systems on
1996 and newer model year vehicles be warrantied for a
minimum of two years or 24,000 miles. Warranty coverage
for the catalytic converter, the electronic emissions control
unit or computer (ECU), and the OBD computer is extended
to eight years or 80,000 miles. Many automakers provide
extended warranty coverage beyond that required by law.
Consult your vehicle’s warranty documents or your dealer for
more information.
What to do with your check
engine light?
If possible do not disconnect the battery or have the
technician clear the codes during repairs. This will turn
the check engine light off and you will not know when the
monitors are reading ready for a follow up test. You want
to receive your repaired vehicle with the check engine light
on, unless the technician had to disconnect the battery to
make the repair.
If the check engine light was able to remain on after the
vehicle is repaired, the vehicle will then need to be driven
through its drive cycle to rerun the monitors (if the correct
repairs are made) and the computer will turn the light off.
When the light goes off then you know when to take the
vehicle in for another OBD II test.
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