Codes Galore

[cjfulton258]

Posted previously about the knock sensor code, and the smart folks on here told me it was not that big of deal, and they were right. I've had no trouble with the 99 QX4, 180k miles. However, I do need to pass an emissions test here in IL, and it certainly will not pass with the Service Engine Light on. I took her up to AutoZone to run current diagnostic and she spit out 3 codes:

P0131-Fuel Ratio Sensor
P0151-Oxygen Sensor
P0325-Knock Sensor

The weird thing is that the Sevice Engine Light goes off for a couple days at a time. It seems like this occurs right after every oil change. Any ideas on why that might be or is this just coincidence? Is there any way to trip this light off so that she can pass emissions?

If not, is it worth fixing the above codes or is she a garner?

Thanks for your help!

[Wkz1gg0a]

In NY if your Knock sensor light is on You Fail. I had the O2 and Knock on. I got the o2 fixed by simple removing it and "cleaning" but the Knock sensor stayed it was about $400 to change that one sensor alone so i payed an extra $50 to my local inspection place and passed lol. I do need that sensor fixed tho. With thos sensor on your gas mileage plumits like hell.