Jaguar Repair: oxygen sensor, combustion chamber engine, nox levels

Question
QUESTION: Hi howard, my name is eddie
Im a new owner of a 1985 jahuar xj6 and am trying to get familiar with the car, based on the fact that i have never owned a jaguar. On the dash it has the oxygen sensor turned on. I tried to change the sensor to see if it would turn off but unfortunately it did not. Is there something u can recommend to do, to have the light turn off?

ANSWER: Hi Eddie,
That is a mileage light warning you it is time to service the 0-2 sensor and you need to go into the trunk and remove the forward panel that covers the ECU and to the left should be a black box with a white button on it. Just push the white button to reset the light. Some were in the left side panel.
Howard

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QUESTION: Sorry i forgot to also ask if wen reseting it does the car have to be on or off?

ANSWER: It is a mechanical reset so it doesn't matter if it is on or off.
Howard

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QUESTION: Hi Howard, so i reset the ECU and the oxygen sensor light on the dash went away.. So today i took the car to smog but it didnt pass due to the fact that its NOx levels are way to high..wat do u prupose is causing that?

Answer
Hi Eddie,
NOX is caused by an over heating of the combustion chamber. Several things can cause this.

Many other brand cars experienced this when the factories put emission control on their engines because they tried to meet emission standards by raising combustion chamber temperature. To counter the production of NOX, they installed EGR to dilute the combustion charge. The XJ-6 ser III did not have EGR so you need to look at any and all things that can over heat the combustion chamber.

Engine temp too high
lean mixture
Incorrect ignition timing
Wrong fuel
Fuel additives (if added)

look at the CO and HC readings of the emission tests and let me know what the readings were.

Howard