Ok ... I have had this issue now for several weeks but I don't fully understand what is going on here. My CEL came on, pulled codes (faulty front oxy sensor, KS). So, replaced the o2 sensor (now for the 4th time in 6 months! ... under warranty) and reset the CEL. About a week later, CEL comes on again ... faulty front oyx again! GGGGRRRRR lol So I left it alone, drove the car, no noticeable difference other than a dip in mpg. I drive an hour and 45 mins to work and home ... and it goes off. And, it stays off ... but then several starts later, it's back on again. It's 'turned it's slef on / off' now ~3 or 4 times over the course of 2 weeks.

What is goin on ??? Also, I don't have any exahust leaks up front (or anywhere for that matter) but I keep eating Oxy sensors?

As always, any and all help is much appreciated!

 

You don't mention the code by number, or which bank it refers to, so I gotta ask - are you sure you are replacing the correct one? There are two primary & one secondary oxygen sensors , you know.

 

P0325 (front bank / left bank pre-cat oxy sensor. Yea, I'm sure it's the right one.

I just ran to the store, last night when I got home, the SES was on - now it's off.

 

Isn't P0325 the knock sensor? (Why are you replacing the O2 sensor instead?)

[Edit: more info] Since it is on and off, you might have bad ground connection. I would try to clean up the two ground bolts in front the the engine. (check http://www.motorvate.ca/mvp.php/507 for more information). Good luck.

 

P0325 is not an oxygen sensor code.

I don't see how you replaced the correct sensor since you do not have the correct code to determine which one it is.

 

Sorry ... was in a hurry earlier, yes P0325 is KS ... I also pull P0147 which is the oxy sensor. Mah bad! lol

Gnd is good .... just replaced it a few months back. No other signs of it being bad.

 

Also, faulty codes for the KS and O2 sensors don't necessarily mean the sensors are bad. Something could be affecting the Air/Fuel ratio, thus causing the KS/O2 codes. MAF, TPS, faulty injector seals, bad fuel pump, or temp sensors could all cause this problem. The KS and O2 will each throw codes when 1 or more of 2 conditions are met: constant voltage, indicating a short/bad sensor, or inability to correct a reading outside of the set parameters, which would indicate a problem other than the sensor.

I had this same problem last summer, and it turned out to be bad fuel rail insulators. I replaced the same O2 sensor twice, when finally, after the third code was thrown, I started to get other codes, like multiple cylinder misfire. Maybe its time to wait to see what other codes are thrown.

 

Excellent post mate ... thank you!

I worked a job on a Mazda minivan once that kept throwing an o2 code. After reading the TSBs and 'national knowen problems' it turned out to be the LIM bushings. I see how the fuel rail insulators could seem to have the same effect, thus causing a similar problem. That may account for the occasional hard start issue and on occasion, a sort of 'kick back' from overloading the fuel rail. I replaced the pump and I checked the FPR, but I get vaccumm when I should so I don't think it's bad. So far, the only codes I have gotten are the KS ghost code and the P0174 oxy. I thought it may be due to an exahust leak, but I don't find one.

How did you figure out it was the insulator bushings, and how hard is it to fix. Does the UIM have to come off? Thanks ... worth looking into.

 

i was gonna say something along those lines but you said it pretty well
my bet is the a/f ratio outside of the stoich range, whatever factors that may be causing that depending on the actual a/f reading and what shudson stated.

why don't you also get a wideband o2?

 

Pure luck. It was nothing else, and out of sheer frustration I just starting breaking everything down. Then the light hit the insulator just right... and I saw a crack. Checked the other five and three of them were beginning to fail.

To get to them, you have to take off the UIM and unbolt the fuel rail. When you flip up the fuel rail, most of them should be stuck to the nozzles, or in the lower plenum. Their cheap to fix, at a little more than $1 each. Just lube and replace.

 

Are you referring to the pintle cap?

 

No, the pintel cap is on the injector itself. The fuel rail insulators are the large quarter sized bushings that sit between the fuel rail and lower plenum.

 

I know what they are, but are you really attributing an O2 sensor code to fuel rail spacers?

 

For the particular code he's throwing, yes, the spacers can be the culprit. P0174 indicates the bank is leaned out. If the spacers are cracked, it will allow air to leak into the intake.

Of course, I'm not suggesting that's the only possible cause. This has got to be one of the most ambiguous code you could throw. Just about anything between the MAF and the rear O2 can cause this code. It was just my case.

 

You think this is bad, you should see some of the EGR and EVAP codes.

If the spacer was faulty in such a way that the rail was propped up slightly, then it's a possibility. However if it was just plain cracked, the rail would sit in the same exact position as it would anyway, and there would be no affect on engine operation.

 

I'll have to disagree. If the spacer is cracked enough, it could allow air through. Mine were so bad I could peel them apart. My fuel rail looked to be seated ok. I didn't fix anything else. I didn't see abnormal wear/impressions on the UIM gasket. Misfire and O2 code gone.

 

Wait, I see the confusion. I'm talking about the fuel rail spacers, you're talking about the rubber seals that go around the base of the injector.

You said it sits between the fuel rail and the LIM, not the injector and the LIM. But yes, those could indeed cause an issue.

 

hey Jtz, sorry to thread-jack you buddy but i'm having the same o2 sensor issue with the constant CEL and your post brought to mind a question.

this "kick back," does it happen at a stop while in drive? cause i occasionally feel a ever so slight jerk, like a 2nd to 1rst kick-down. i would think this was normal but, more than once??

anyway, your solution may solve my problem too so... good luck!

 

Misfiring under load at idle is most often a weak/failing coil.

 

No ... not under load, only at start up. Not every time will it 'kick back' either, just on occasion. Car drives great, idles fine, no real change in mpg. My CEL comes on and off about once a week or so .... never had this issue on any other car.

I can understand how a faulty seal / bushing would cause an a/f ratio mishap but I'm not convinced that is the issue here. I sprayed carb cleaner around each injector (rears were fun! ) and no change in idle or engine pitch .... so I dunno. I think for the hell of it, I'll pull the UIM and fuel rail, replace the insulators and clean my EGR while I'm at it. I've had bad fuel injector seats before (on my Stanza) but with the seal being bad on that ... I got the aroma of fuel and I don't here.

I do agree that P0174 is not a 'deffinative' code at all ... sadly! But refers like mentioned to a 'lean left bank'. I'd almost feel better if it were both banks. lol

 

Any other takers on this? Anyone else have this issue?

 

<--- Knows nothing about cars. Knows a little bit about electricity.

I had my CEL come on for a bunch of stuff Throttle Position Sensor, KS and one or two others possibly O2. All of the codes were ones that stated something like "the ECM has received an excessive high/low voltage from sensor". It turned out to be a charging issue. My car was running a high voltage (15 + voltages for a short time) which appeared in turn to cause the computer to think everything was blown. Reset CEL and haven't had it happen since.

If its intermittent I don't know if simply checking the voltages on the alternator and battery would work. I had a digital voltage meter on my car because of my stereo. So when the CEL came on I saw that my voltage was like 15 something and knew that was odd.

Probably won't help but worht a shot, maybe the alt is messed up or something. Oh and by the way, the voltage was high cause it was super cold out that day. So if this started happening when it got warm out in your area seems like the electrical issue might have something to do with it.


Good luck.

 

Thanks for the input. That seems odd that weather would affect the charging system like that but starnge things happen to 10 + y/o cars! lol

I run a cap on my system as well and it's steady at 14.1v and the alt is only ~6 months old. Car seems to run fine, it's just an anoyance having that stupid light on. However, I don't want to just pull the bulb or anything, I'd like to fix it so it goes out. lol Still working at it ... has to be something causing it.