Preventing catalyst damage during misfire event

1. A control system comprising:

a first electronic circuit configured to:

apply voltage pulses at a first duty cycle to a heating element of an oxygen sensor;

determine a first temperature of the heating element; and

apply voltage pulses, at a second duty cycle, to heat the heating element to a predetermined temperature in response to the first temperature being greater than a first threshold temperature, wherein the first duty cycle is greater than the second duty cycle;

a second electronic circuit configured to determine a temperature of exhaust gas based on a resistance of the heating element and the second duty cycle; and

a third electronic circuit configured to adjust an operating parameter of an engine to decrease the temperature of the exhaust gas when the temperature of the exhaust gas is greater than a second threshold temperature, wherein the second threshold temperature is based on a temperature that damages a catalyst in an exhaust system.

2. The control system of claim 1 wherein the second threshold temperature is greater than 800° C.

3. The control system of claim 1 further comprising the first electronic circuit is further configured to electrically heat the heating element to an operating temperature of the oxygen sensor and that stops electrically heating the heating element when the temperature of the heating element is greater than the operating temperature, wherein the operating temperature is less than the second threshold temperature.

4. The control system of claim 1 wherein the third electronic circuit is further configured to adjust at least one of fuel injection and a position of a throttle to decrease the temperature of the exhaust gas.

5. The control system of claim 1 wherein the third electronic circuit is further configured to determine when combustion events on the catalyst resulting from misfires in the engine are heating the exhaust gas to a temperature that is greater than the second threshold temperature.

6. The control system of claim 5 wherein the third electronic circuit is further configured to adjust the operating parameter of the engine to prevent combustion events on the catalyst.

7. The control system of claim 5 wherein the third electronic circuit is further configured to determine that combustion events on the catalyst resulting from misfires in the engine are heating the exhaust gas based on the resistance of the heating element, wherein the heating element is located downstream from the catalyst.

8. The control system of claim 5 wherein the third electronic circuit is further configured to determine that combustion events on the catalyst resulting from misfires in the engine are heating the exhaust gas based on the resistance of the heating element, wherein the heating element is located upstream from the catalyst.

9. The control system of claim 1 wherein, based on the resistance of the heating element, the third electronic circuit is further configured to determine when heating of the exhaust gas to a temperature that is greater than the second threshold temperature is a result of a load on the engine.

10. The control system of claim 9 wherein the third electronic circuit is further configured to adjust the operating parameter of the engine to decrease the load on the engine.

11. A method comprising:

applying voltage pulses at a first duty cycle to a heating element of an oxygen sensor;

determining a first temperature of the heating element;

applying voltage pulses, at a second duty cycle, to heat the heating element to a predetermined temperature in response to the first temperature being greater than a first threshold temperature, wherein the first duty cycle is greater than the second duty cycle;

determining a temperature of exhaust gas based on a resistance of the heating element and the second duty cycle; and

adjusting an operating parameter of an engine to decrease the temperature of the exhaust gas when the temperature of the exhaust gas is greater than a second threshold temperature, wherein the second threshold temperature is based on a temperature that damages a catalyst in an exhaust system.

12. The method of claim 11 wherein the second threshold temperature is greater than 800° C.

13. The method of claim 11 further comprising:

electrically heating the heating element to an operating temperature of the oxygen sensor: and

stopping electrical heating of the heating element when the temperature of the heating element is greater than the operating temperature, wherein the operating temperature is less than the second threshold temperature.

14. The method of claim 11 further comprising adjusting at least one of fuel injection and a position of a throttle to decrease the temperature of the exhaust gas.

15. The method of claim 11 further comprising determining when combustion events on the catalyst resulting from misfires in the engine are heating the exhaust gas to a temperature that is greater than the second threshold temperature.

16. The method of claim 15 further comprising adjusting the operating parameter of the engine to prevent combustion events on the catalyst.

17. The method of claim 15 further comprising determining that combustion events on the catalyst resulting from misfires in the engine are heating the exhaust gas based on the resistance of the heating element, wherein the heating element is located downstream from the catalyst.

18. The method of claim 15 further comprising determining that combustion events on the catalyst resulting from misfires in the engine are heating the exhaust gas based on the resistance of the heating element, wherein the heating element is located upstream from the catalyst.

19. The method of claim 11 further comprising determining, based on the resistance of the heating element, when heating of the exhaust gas to a temperature that is greater than the second threshold temperature is a result of a load on the engine.

20. The method of claim 19 further comprising adjusting the operating parameter of the engine to decrease the load on the engine.

21. The control system of claim 1 further comprising at least one of an Application Specific Integrated Circuit (ASIC), a processor and memory that execute one or more software or firmware programs, and a combinational logic circuit that includes the first electronic circuit, the second electronic circuit, and the third electronic circuit.