Functions of catalytic converters & Faults

Functions of catalytic converters & Faults

Catalytic converters are a crucial component of modern automotive engines that help to reduce the harmful emissions produced by vehicles. They work by converting pollutants into less harmful substances through a series of chemical reactions. However, just like any other part of a car, catalytic converters can fail over time. In this article, we will explore the functions of catalytic converters, common causes of failure, and how to fix them. We will also discuss some of the common DTCs (Diagnostic Trouble Codes) associated with catalytic converter failure.

Functions of Catalytic Converters
The primary function of catalytic converters is to reduce harmful emissions from a vehicle's exhaust system. They achieve this by converting harmful pollutants, such as carbon monoxide, hydrocarbons, and nitrogen oxides, into less harmful substances like carbon dioxide, water, and nitrogen. This process occurs through a series of chemical reactions that take place within the catalytic converter.
Catalytic converters contain a honeycomb-like structure made up of a ceramic material coated with precious metals, such as platinum, palladium, and rhodium. These metals act as catalysts, speeding up the chemical reactions that occur within the converter. The structure of the converter forces the exhaust gases to pass over and through the honeycomb, where the chemical reactions take place.

Causes of Catalytic Converter Failure
There are several reasons why a catalytic converter may fail. The most common causes include:

1. Contamination: Over time, contaminants such as oil, coolant, and unburned fuel can accumulate within the converter. This can cause the honeycomb structure to become clogged, reducing its effectiveness.
2. Physical damage: Catalytic converters can be damaged by impact, such as hitting a speed bump or pothole, which can cause the honeycomb structure to crack or break.
3. Overheating: A catalytic converter can overheat if the engine is running too hot or if there is a problem with the ignition system. This can cause the honeycomb structure to melt or collapse.
4. Age: Over time, the precious metals within the converter can become depleted, reducing its effectiveness.

How to Fix a Failed Catalytic Converter
If a catalytic converter has failed, it will need to be replaced. However, before replacing the converter, it is important to identify the underlying cause of the failure. This will help prevent the new converter from failing prematurely.
If the failure was due to contamination, it is important to identify and repair the underlying issue, such as a leaking head gasket or faulty fuel injectors. Once the issue has been resolved, the converter can be replaced.
If the converter was damaged due to impact, it will need to be replaced. It is important to also inspect the exhaust system for any other damage that may have occurred.
If the converter overheated due to a problem with the ignition system, such as a misfiring spark plug, it is important to repair the ignition system before replacing the converter.

Common DTCs Associated with Catalytic Converter Failure
When a catalytic converter fails, it can trigger several DTCs. Some of the most common include:

1. P0420: Catalyst System Efficiency Below Threshold (Bank 1)
2. P0430: Catalyst System Efficiency Below Threshold (Bank 2)
3. P0421: Warm-Up Catalyst Efficiency Below Threshold (Bank 1)
4. P0431: Warm-Up Catalyst Efficiency Below Threshold (Bank 2)
5. P0422: Main Catalyst Efficiency Below Threshold (Bank 1)
6. P0432: Main Catalyst Efficiency Below Threshold (Bank 2)

These DTCs indicate that the catalytic converter is not functioning properly and may need to be replaced. However, it is important to diagnose the underlying issue before replacing the converter

1. P0423: Heated Catalyst Efficiency Below Threshold (Bank 1)
2. P0433: Heated Catalyst Efficiency Below Threshold (Bank 2)
3. P2096: Post Catalyst Fuel Trim System Too Lean (Bank 1)
4. P2097: Post Catalyst Fuel Trim System Too Rich (Bank 1)
5. P2098: Post Catalyst Fuel Trim System Too Lean (Bank 2)
6. P2099: Post Catalyst Fuel Trim System Too Rich (Bank 2)

​
These DTCs indicate that there is an issue with the fuel trim system, which can cause the catalytic converter to fail. It is important to diagnose the underlying issue before replacing the converter.

Catalytic converters play a vital role in reducing harmful emissions from vehicles. However, they can fail over time due to a variety of reasons, including contamination, physical damage, overheating, and age. If a catalytic converter fails, it will need to be replaced, and it is important to identify and repair the underlying issue to prevent premature failure of the new converter. Finally, if a DTC is triggered due to catalytic converter failure, it is essential to diagnose the underlying issue before replacing the converter.