Victim64

I allways use Premium gas 91 and up. I have had the knock sensor code twice on my car in the past 6 months. I have never heard my engine knock though. My guess is that the it is being to sensitive, but thought I would get some input. Oh, I am getting the UPRD ECU soon, will this make this worse??

emax02

iTrader: (1)

I remember I watched like 60 Minutes or something and they found lots of no name/name gas stations with less then rated octane levels in many cases.So try to only get gas from places like mobil/sunoco/shell.I have never had any knock sensor problems before or after the UPRD ECU since I only use Sunoco 93 or Ultra 94 gas.

Victim64

I use the same gas stations that I have since I got the car two and a half years ago, so I am not sure what the problem is....Might be nothing, last time the light came on it was the knock sensor and Temp sensor, and I have never seen my temp gauge go up farther than half way so you got me

JULIAN

iTrader: (3)

is going bad, I had a code 34 that came on for the KS several times and I kept resetting it, finally I replaced it and so far the code never came back.

Victim64

So how much was that, and where is it located at? Also, if I don't do it for awhile, will it cause a problem other than my light going off all the time??

JULIAN

iTrader: (3)

so the rear one shoudld be back there somewhere but I really do not know where since I was not paying attention since mine was the front one. But I do know since my KS was bad it kept retarding my timing when I checked it with my timing light to about 8-10 degrees where as normal is like 15 degrees +/- 2 degrees, so my car was feeling very sluggish, and I am always using Amaco93 octane.

Daniel B. Martin

Here is some information about the Knock Sensor, taken from the '99 Maxima factory service manual.

1) Raise the hood. View the engine from the driver's fender. Look into
the deep valley between the cylinder banks and below the intake manifold.
Identify the KS as a black item fastened to the block by a single vertical
bolt. A wire harness wrapped in black leads toward you, out of the valley.
That is the KS sub-harness.

2) Follow the KS sub-harness to it's nearest connector. This is connector F121.
It is located near the upper right-hand corner of the valve
cover of the forward cylinder bank, as viewed from the
front of the car.

3) Disconnect F121. You have to do a "press the latch and wiggle and
pull" to disconnect it. F121 has only two pins; if you see more than two
pins, you have the wrong connector. Use a digital ohmmeter capable of
measuring more than 10 Megohms. You want to measure the pins of F121, not
the sockets of the matching connector. Measure the resistance between a
good ground (such as the battery negative terminal) and pin #2 of connector
F121. On my car this is the highest of the two pins, the one closest to
the front of the car. The factory spec is 500 - 620 Kohms.

The manual says you have to remove the intake manifold to replace the KS. However, I think that a person with good dexterity and a 10mm ratcheting box wrench could replace the KS without disturbing the manifold.

JULIAN

iTrader: (3)

that you DO NOT have to remove the intake manifold. I was able to change mine out by smushing my hand under the tunnel area of the intake manifold and using either a 10 mm or was it a 12 mm ratcheting box wrench, which in my opinion is better in this situation than a socket, that way you can use your fingers to feel for the bolt. It took me like 15 minutes to change it out, but my hands got all cut up from all the sharp edges in there. You can't use gloves because you need to feel your way in there especially the bolt. It was worth it, the dealer wanted like $75-100 to change it out, because they said that they have to take the intake manifold off. With great lighting you can actually see the Knock Sensor under the intake manifold. Good Luck !!!!!