Three Way Catalytic Converter (TWC), Checking

General Description

A catalytic converter is a vehicle emissions control device that converts toxic pollutants in exhaust gas to less toxic pollutants by catalyzing a redox reaction (oxidation or reduction). Catalytic converters are used in internal combustion engines.

General recommendations

Oxygen sensors OK.

No leaks or damage to exhaust system.

Prior to repair work, perform a preliminary check to verify the condition. Refer to PRELIMINARY CHECK .

Test Requirements

Fuses OK.
Battery voltage OK.
Switch OFF all electrical and electronic accessories.
Vehicles with automatic transmission, ensure the selector lever position is in "P".
Vehicles with manual transmission, ensure the shifter lever position is in "N" with the parking brake applied.
Observe all safety precautions: SAFETY PRECAUTIONS .
View clean working conditions: CLEAN WORKING CONDITIONS .

Test Procedure

Step	Procedure	Result / Action to Take
1	Activate Monitors: Perform the function test in Diagnostic Mode 06. Refer to appropriate Diagnostic Mode 06 - Read Test Results for Specific Diagnostic Functions, DIAGNOSTIC MODES 01 - 0A . End diagnosis and switch the ignition off. If the specified values are exceeded:	Check the exhaust system for leaks. If necessary, repair the leak(s) in the exhaust system. GO TO: Step 2 THREE WAY CATALYTIC CONVERTER (TWC), CHECKING - 2 .
2	O2 Sensor Monitoring: Erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY . Perform a road test to verify repair. If the DTC does not return:	Generate readiness code. Refer to READINESS CODE . If no leaks are found in the exhaust system: Replace the catalytic converter with front exhaust pipe. Refer to appropriate service information. GO TO: Step 3 THREE WAY CATALYTIC CONVERTER (TWC), CHECKING - 3 .
3	Final procedure: Perform a road test to verify repair.	After the repair work, the following work steps must be performed in the following sequence: Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY . If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY . If the DTC memory was erased, generate readiness code. Refer to READINESS CODE . Return vehicle to Customer.