Guest path1998 Posted August 25, 2006 Share Posted August 25, 2006 Like many others Pathy riders, I got finally that delightful light "service engine soon". I went to autozone to get the code read and they told me that it could be an O2 sensor or the knock sensor. After that episode, I brought my PF98 to two autorepair shops and both of them told me that I have to replace the knock sensor. Well, in conclusion, it's gonna cost me about 500 bucks to replace it. Searching on ebay, I found the sensor for 60 bucks, including shipping and I am thinking to replace it myself, so the million dollar question is: It's worth to try it?, I know that it's gonna be painful to pull out those two manifolds, but how difficult that could it be?. That was the first part of the message, the second part is about two noises that are driving me crazy. Both of them come from front of the truck and one of them sounds like a bearing running out of grease. I have replace the rotors and the pads, but the noise is still there. That noise only can be heard only when the car is in movement and it is independent of the speed. I am wondering if the wheel bearing could produce such a noise?. The last part of this long message is about to begin!. About three month ago, I started to hear an oscilatory noise coming from somewhere in the front. The frequency of the noise is increasing with the speed of the car, so I thought that could be related to some of the front axis, but I don't feel any vibration on the steering wheel, so it cannot be anything directly related with the wheels. I also thought in the transmission, but I replaced it only a year ago, and besides, when I touch the shift lever I don't feel anything. The noise is audible at 34 mph and the amplitud and frequency of the vibration increases almost linearly with the velocity. I have checked the front axis and driveshaft and they are tight, but it is hard to say if the problem is there when the car is parked. Any suggestions are welcome and I hope you did not get too bored reading all of this, thanks. Link to comment Share on other sites More sharing options...
lewisnc100 Posted August 25, 2006 Share Posted August 25, 2006 Don't change the knock sensor, it won't trigger the CEL. My light is off and if I check the codes I'll have a knock sensor error code everytime, but I've never had any issues. If you're CEL is on then you have another code other than a knock sensor code. Can you post the actual code number(s) you are getting. For the front end noise, when's the last time you repacked your bearings? Link to comment Share on other sites More sharing options...
Guest path1998 Posted August 25, 2006 Share Posted August 25, 2006 the codes I've got are: P0325 (knock sensor) and P1440 (manufacture control...). I haven't finished yet all the tests to the O2 sensors, I just measured continuity on them and everything was normal. About the bearing, I haven't repacked them since I bought the truck, which was on Feb 2003 with 54000 on it, now it has 74000. I thought that when the guys in the autorepair shop replaced the rotors, also they replaced the bearing, but problably I am wrong and that could be one of the noises that I can hear. But the other noise definitely is not coming from the bearings, cause the frequency is too low. When I am driving the car at 33 mph, the frequency is roughly 3Hz, so what could it be?. That kind of noise arises from the fact that the center of mass of some component is not located right at the center of the axle rotation, that means that something is loose or an axle is not straight or something similar, but I just haven't been able to identify what is the component that is producing such noise. Link to comment Share on other sites More sharing options...
XPLORx4 Posted August 25, 2006 Share Posted August 25, 2006 P1440 is an EVAP error code. Something's amiss with your EVAP system. It could be as simple as a loose gas cap or a loose vacuum hose in the EVAP system. As previously stated, you can ignore the P0325. I've had that code for 3 years now, and haven't had any problems. The other noises you're hearing are likely due to failed bearings. Since they're making noise, it's probably too late to just repack them. You'll probably need to replace them. A brake job does not automatically include bearing repacking. Did the noises occur after the brake job was done? You may be able to take the truck back to the shop who replaced your rotors and find out if they forgot to put something back together correctly. Just out of curiousity, why didn't you do the brakes yourself? It sounds like you were prepared to change the knock sensor yourself (which looks to be a royal pain in the butt). The brakes (and bearings) are way easier, albeit a little messy. Link to comment Share on other sites More sharing options...
Guest path1998 Posted August 25, 2006 Share Posted August 25, 2006 Well, I didn't replace the brakes myself just because I don't have a place to do it. I live in an apartment and it is not allowed to do any maintenance in the parking lot. Both noises were there before and after the brake job. Thanks for the tips, I'll ckeck the hoses in the EVAP sys. About the noises, I guess I'll go for a bearing replacement and see what happen, but to me it is unlikely that the two noises would come from the same part (bearings). I'll be very surprised if the two noises go away after raplacing the bearings, but if that happen, I'll share the information. By the way, I just wanna say that it is really cool to have a site like this to share PF's experiences. Link to comment Share on other sites More sharing options...
vengeful Posted August 25, 2006 Share Posted August 25, 2006 Dean, You say you've had the KS code for 3-years? How do you pass smog? Path98, Generally, in order to replace the rotors on a Pathfinder, you have to repack the wheel bearings. If the bearings weren't repacked, there's a good possibility that they are off-center. Link to comment Share on other sites More sharing options...
XPLORx4 Posted August 25, 2006 Share Posted August 25, 2006 Dean, You say you've had the KS code for 3-years? How do you pass smog? The knock sensor DTC doesn't illuminate the MIL, so it's not an issue for the CA smog test. Link to comment Share on other sites More sharing options...
Guest path1998 Posted August 25, 2006 Share Posted August 25, 2006 but if one of the bearing is out of center, shouldn't I feel some vibration on the steering wheel? (which does not happen in my case). What are the common symptoms for a bearing problem? Link to comment Share on other sites More sharing options...
vengeful Posted August 25, 2006 Share Posted August 25, 2006 When my wheels were bent/out of balance, it would vibrate the brake dust sheild against something and create an awful racket between 15-20mph. Not sure if that's whats going on with yours, but it might be something along those lines. Link to comment Share on other sites More sharing options...
vengeful Posted August 25, 2006 Share Posted August 25, 2006 The knock sensor DTC doesn't illuminate the MIL, so it's not an issue for the CA smog test. Wierd...and here I thought CA had the smog nazis...VA wouldn't pass me because the KS DTC was present. pssd Link to comment Share on other sites More sharing options...
XPLORx4 Posted August 25, 2006 Share Posted August 25, 2006 path1998- First address the bearing problem. Don't worry about the other noise yet. Chances are that they're related somehow. Again, if this happened AFTER you got the truck back from the shop who did your brakes, take it back and have them take a look at it. Link to comment Share on other sites More sharing options...
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