Catalytic Converters
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.