Hi, I am new to the club and I am sure this topic has come up before. I just bought a 2000 X 3.3 (XE) and the other day I had the ses light come on, I ran the code reader got these two codes 325 (knock sensor) and 128 (O2 sensor). When we ran the codes we noticed that the car was runing rich would this mean that the knock sensor is bad since it setting off the O2 sensor? Now I am not sure what to do since I have read in previous posts that the knock sensor does not need to be replaced on these engines? I thought since the truck was sitting for a few months I thought it might have been the gas, I used lucas fuel treatment but the codes came back after a week. We just cleared the codes but the truck seems to idle a little rough? Would a bad O2 sensor make it run rich? Can I switch the rear sensors to see if I get a bank one code rather than bank 2 to rule out a bad sensor? Any suggestions would be greately appreciated.

The KS code can be ignored, and they luckily have nothing to do with each other.

The O2 can definitely change the richness though, as the more air, the less rich, etc.

The MAF sensor can be off as well, especially if fouled/dirty.

Swapping sensors can help narrow the diagnosis down.


BTW - The KS makes a difference on the SC engines that came out in 2002 - 2004, but not on the 2000 - 2001 X's, or the NON-SC 2002 -2004's.


It can also run rich if the air filter is too restrictive/dirty for example.

TJ, I was thinking of cleaning the MAF sensor can that be done without screwing up the sensor? If so what do you recommend? Next I will replace the air filter to ruleout all the inexpensive fixes, if that doesn't do the trick than I will change out the O2 sensor. If I find that both sensors need to be replaced what's a good place or brand name that I should use? TJ thanks for all the good information.

Use MAF cleaner, not brake cleaner, etc...and be gentle.



It can take the ECU some time to sort out changes as well, so you need to give it as much as 500 miles after a change, to see the affect.

TJ or any member reading this post,

Why is it that for my 2000X or 2000-04 non SC models that the knock sensor does not come into play or is ignored when you get that code? Does the sensor not serve a purpose? Just curious...

I have also heard that one should replace their O2 sensors after 100, 000 miles is that true? The reason why I ask is that my X has 104k miles and I am having to replace the original O2 sensor due to a code.

Also, what after market O2 sensor if any would you recommend? I spoke with someone at nissan parts and he didn't recommend to use after market parts but he suggested Bosch???

Thanks for all the input.

JR

The KS just detects knock.

If there's so need to adjust the timing to account for the knock, you don't even need the sensor.

The KS will throw a code of concern on the non-sc engines, because they don't need premium.

The SC can knock if you use regular instead of premium, and, therefore, the ECU etc, considers the KS to be more important, as it WILL need to change the timing if you use the wrong gas.

If you put premium in a non-sc engine, it will do the opposite of knock (Push the piston late, wasting energy, but not push it early as happens in ping and knock, etc.)

Bosch is fine for the 02 sensor