The law requires you to
have a catalytic converter on your vehicle. (Well, most vehicles,
anyway.) But what does a catalytic converter actually do? Why do
you need one?
HOW DOES A CATALYTIC CONVERTER WORK?
Use the FLASH animation below to explore your vehicle's
catalytic converter.
Catalytic converter Q. and A.
Question
How do I know when the catalytic converter on my vehicle needs to
be replaced?
Answer
The best way to determine if the catalytic converter has failed
is by testing the exhaust with testing procedures like those used
in state and local inspection programs. However, the following
symptoms may also indicate a need for converter replacement:
Broken or rusted out converter body or end tubes.
Bits of substrate in other sections of the exhaust system.
No rattle in a pellitized converter (If the converter doesn't
rattle, the pellets may have melted together or fallen out.
A rattle in a monolithic converter (A rattle in this kind
of converter indicates the substrate has separated.)
Question
My Technician was talking about the OBDII on my vehicle.
What is that?
Answer
OBDII references the second generation of On Board Diagnostic
used initially in California and now in all 50 states. It is a
computerized engine and emission monitoring system designed to
alert the driver that emission control service is needed.
Question
What is the connection between OBD and Vehicle emissions?
Answer
The vehicle computer will detect a system problem before the
driver notices a driveability problem. OBD can also detect problems
that might be noticed by visual inspection because they can be
electrical or even chemical in nature. By detecting these emissions-related
failures and alerting the driver to the need for potential repair,
EPA hopes that vehicles will be properly repaired before emissions
become a problem.
Question
How does OBD inform drivers of problems?
Answer
When the OBD system determines that a problem exists, a corresponding
"Diagnostic Trouble Code" is stored in the computer's
memory. The computer also illuminates a dashboard light indicating
"Service engine Soon" or "Check Engine" or
displays an engine symbol. This light, usually yellow in color,
serves to inform the driver that a problem has been detected and
vehicle service is needed. When the vehicle is delivered to the
repair shop, a technician can retrieve the stored diagnostic trouble
codes from the computer memory of the vehicle. It is important
to note that an illuminated dashboard light, as described here,
is intended to inform the driver of the need for service, NOT
of the need to stop the vehicle. However, service should be sought
as soon as possible. Drivers may also wish to consult a repair
shop or their vehicle owner's manual for further guidance.
Question
Why does the dashboard light blink or flash?
Answer
Under certain conditions, the dashboard light will blink or
flash. This indicates a rather severe level of engine misfire.
When this occurs, the driver should reduce speed and seek service
as soon as possible. Sever engine misfire over only a short period
of time can seriously damage emission control system components,
especially the catalytic converter, which is typically the most
expensive to replace. Drivers should also consult their vehicle
owner's manual for manufacturer specific instructions.
Question
How can the dashboard light be turned off?
Answer
After fixing the problem, the service technician will reset
the fault codes, turning off the dashboard light. The vehicle's
OBD system can turn off the dashboard light automatically if the
conditions that caused a problem are no longer present. For example,
if the gas cap is not properly tightened after refueling, the
OBD system can detect the vapor leak that exists. If the gas cap
is tightened, the dashboard light should be extinguished within
a few drives.
Question
How does OBD help the environment?
Answer
The intent of OBD systems is to assure proper emission system
operation of all vehicles over its lifetime by monitoring emission
related components and systems for malfunction and/or deterioration.
An important aspect of OBD is its ability to notify the driver
of a problem before the vehicle's emissions have increased significantly.
If the vehicle is taken to a repair shop in a timely fashion,
it can be repaired before any significant emission increase occurs.
Question
How does OBD help consumers?
Answer
OBD systems are designed to alert drivers when something in
the emission control system begins to deteriorate or fails. Early
diagnosis followed by timely repair can often prevent more costly
repairs on both emission control systems and other vehicle systems
that may effect vehicle performance such as fuel economy. For
example: a poorly performing spark plug can cause the engine to
misfire, a condition sometimes unnoticed by the driver. The engine
misfire can, in turn, quickly degrade the performance of the catalytic
converter. With an OBD detection of the engine misfire, the driver
would be faced with a relatively inexpensive spark plug repair.
However, without an OBD detection, the driver could be faced with
an expensive catalytic converter repair in addition to the spark
plug repair. OBD systems also provide far more information than
ever before to help auto technicians properly diagnose and repair
vehicles during periodic maintenance, or their first visit to
the repair shop, saving time and money for consumers.
