Diagnostic system and method for an oxygen sensor positioned downstream from a catalytic converter

1. A system comprising:

an actuator of an engine;

a first electronic circuit configured to diagnose a fault in at least one of an oxygen sensor and a catalytic converter based on input received from the oxygen sensor;

a second electronic circuit configured to disable the fault diagnosis based on a temperature of the catalytic converter and a mass flow rate of air flowing through the catalytic converter;

a third electronic circuit configured to determine a total mass of air flowing through the catalytic converter by integrating multiple values of the mass flow rate of air flowing through the catalytic converter with respect to time, wherein the second electronic circuit is configured to disable the fault diagnosis based on the total mass of air flowing through the catalytic converter; and

a fourth electronic circuit configured to adjust the actuator of the engine to adjust an amount of at least one of air and fuel provided to a cylinder of the engine, and thereby adjust an air/fuel ratio of the engine, based on the input received from the oxygen sensor.

2. The system of claim 1 , wherein the second electronic circuit is configured to disable the fault diagnosis based on the total mass of air flowing through the catalytic converter when the temperature of the catalytic converter is greater than a first temperature.

3. The system of claim 2 , wherein the second electronic circuit is configured to disable the fault diagnosis when the total mass is less than or equal to a first mass.

4. The system of claim 3 , wherein the first temperature is predetermined to combust elements in the catalytic converter that cause a response time of the oxygen sensor to temporarily increase.

5. The system of claim 4 , wherein the first mass is predetermined to remove the elements from the catalytic converter.

6. The system of claim 1 , wherein the second electronic circuit is configured to disable the fault diagnosis based on an amount of time that an engine is running when the temperature of the catalytic converter is greater than a predetermined temperature.

7. The system of claim 1 , further comprising a fifth electronic circuit configured to determine the temperature of the catalytic converter.

8. The system of claim 7 , wherein the fourth electronic circuit is configured to determine the temperature of the catalytic converter based on input received from a temperature sensor located at the catalytic converter.

9. The system of claim 7 , wherein the fourth electronic circuit is configured to determine the temperature of the catalytic converter using a mathematical model.

10. The system of claim 1 , wherein the first and second electronic circuits include at least one of an Application Specific Integrated Circuit (ASIC), a processor and memory including one or more programs, and a combinational logic circuit.

11. The system of claim 1 , wherein the fourth electronic circuit controls the actuator of the engine independent of the input received from the oxygen sensor when a fault is diagnosed in the oxygen sensor.

12. The system of claim 1 , further comprising the actuator of the engine, wherein the actuator includes at least one of a fuel injector and a throttle valve.

13. A system comprising:

an actuator of an engine;

a first electronic circuit configured to diagnose a fault in at least one of an oxygen sensor and a catalytic converter based on input received from the oxygen sensor;

a second electronic circuit configured to disable the fault diagnosis based on:

at least one of a temperature of the catalytic converter and a mass flow rate of air flowing through the catalytic converter; and

a total mass of air flowing through the catalytic converter when the temperature of the catalytic converter is greater than a first temperature;

a third electronic circuit configured to:

determine the total mass of air flowing through the catalytic converter by integrating multiple values of the mass flow rate of air flowing through the catalytic converter with respect to time; and

set the total mass to zero based on at least one of: (i) when a vehicle is manufactured; and (ii) input received from a diagnostic service tool; and

a fourth electronic circuit configured to adjust the actuator of the engine to adjust an amount of at least one of air and fuel provided to a cylinder of the engine, and thereby adjust an air/fuel ratio of the engine, based on the input received from the oxygen sensor.

14. The system of claim 13 , wherein the fourth electronic circuit controls the actuator of the engine independent of the input received from the oxygen sensor when a fault is diagnosed in the oxygen sensor.

15. The system of claim 13 , further comprising the actuator of the engine, wherein the actuator includes at least one of a fuel injector and a throttle valve.

16. A method comprising:

diagnosing a fault in at least one of an oxygen sensor and a catalytic converter based on input received from the oxygen sensor;

measuring at least one of a temperature of the catalytic converter and a mass flow rate of air flowing through the catalytic converter;

determining a total mass of air flowing through the catalytic converter by integrating multiple values of the mass flow rate of air flowing through the catalytic converter with respect to time;

disabling the fault diagnosis based on the temperature of the catalytic converter, the mass flow rate of air flowing through the catalytic converter, and the total mass of air flowing through the catalytic converter; and

adjusting an actuator of an engine to adjust an amount of at least one of air and fuel provided to a cylinder of the engine, and thereby adjust an air/fuel ratio of the engine, based on the input received from the oxygen sensor.

17. The method of claim 16 , further comprising disabling the fault diagnosis based on the total mass of air flowing through the catalytic converter when the temperature of the catalytic converter is greater than a first temperature.

18. The method of claim 17 , further comprising disabling the fault diagnosis when the total mass is less than or equal to a first mass.

19. The method of claim 18 , wherein the first temperature is predetermined to combust elements in the catalytic converter that cause a response time of the oxygen sensor to temporarily increase.

20. The method of claim 19 , wherein the first mass is predetermined to remove the elements from the catalytic converter.

21. The method of claim 16 , further comprising disabling the fault diagnosis based on an amount of time that an engine is running when the temperature of the catalytic converter is greater than a predetermined temperature.

22. The method of claim 16 , further comprising determining the temperature of the catalytic converter.

23. The method of claim 22 , further comprising determining the temperature of the catalytic converter based on input received from a temperature sensor located at the catalytic converter.

24. The method of claim 22 , further comprising determining the temperature of the catalytic converter using a mathematical model.

25. The method of claim 16 further comprising controlling the actuator of the engine independent of the input received from the oxygen sensor when a fault is diagnosed in the oxygen sensor.

26. A method comprising:

diagnosing a fault in at least one of an oxygen sensor and a catalytic converter based on input received from the oxygen sensor;

measuring at least one of a temperature of the catalytic converter and a mass flow rate of air flowing through the catalytic converter;

determining a total mass of air flowing through the catalytic converter by integrating multiple values of the mass flow rate of air flowing through the catalytic converter with respect to time;

disabling the fault diagnosis based on:

at least one of the temperature of the catalytic converter and the mass flow rate of air flowing through the catalytic converter; and

the total mass of air flowing through the catalytic converter when the temperature of the catalytic converter is greater than a first temperature;

setting the total mass to zero based on at least one of: (i) when a vehicle is manufactured; and (ii) input received from a diagnostic service tool; and

adjusting an actuator of an engine to adjust an amount of at least one of air and fuel provided to a cylinder of the engine, and thereby adjust an air/fuel ratio of the engine, based on the input received from the oxygen sensor.

27. The method of claim 26 further comprising controlling the actuator of the engine independent of the input received from the oxygen sensor when a fault is diagnosed in the oxygen sensor.