An indicator of the condition of the catalytic converter is its oxygen capacity. As the catalytic converter ages, its oxygen capacity decreases as well as its ability to neutralize exhaust gases.
Conditions for starting diagnostics
Catalytic converter diagnostics can only be performed if the pre-ignition conditions are met and are being fulfilled.
- no electrical faults;
- no misfires detected;
- programming done;
- the main and dual circuits for regulating the mixture composition are activated based on signals from oxygen sensors;
- the engine speed read from the diagnostic tool is within the range of 1120-1840 min⁻¹.
Troubleshooting
Diagnostics are performed while maintaining the engine load within 20-30% and the crankshaft speed within 1120-1840 min⁻¹. If the diagnostic start conditions are met, the mixture enrichment process is delayed in time, which leads to the flow of oxygen portions into the catalytic converter. If the catalytic converter is operational, it absorbs oxygen and the signal voltage value of the lower oxygen sensor remains at an average level. If the catalyst has exhausted its resource, oxygen is not absorbed and the oxygen sensor begins to work continuously. The signal voltage of the oxygen sensor will fluctuate. The on-board diagnostics system warning lamp will light after three consecutive trips. Diagnostics of the catalytic converter lasts 60 s.
Warning! At the end of this toast, do not under any circumstances turn off the ignition before reading the result on the diagnostic device. Turning off the ignition leads to incorrect interpretation of the results.
Confirmation of repair
"On-Board Diagnostics Catalytic Converter Diagnostics: Completed": "ACTIVE".
"Catalytic converter malfunction": "INACTIVE".
If the diagnostic device shows "On-board diagnostic system diagnostics: catalytic converter: failed. ACTIVE", then the control loop is executed incorrectly. In this case, repeat the monitoring cycle in strict compliance with the diagnostic conditions.
If the diagnostic tool displays the message "Catalytic Converter Malfunction ACTIVE" or "Catalytic Converter Repair Confirmation 2DEF" after the test, refer to the diagnostic method corresponding to the malfunction.