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Discussion Starter · #1 ·
What do the oxygen sensors do, and how important is that I replace the two upstream ones. The local (Ford) dealer wants over $400. My truck is a 2002 crew cab s/c long bed.
Thanks in advance~
 

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Discussion Starter · #3 ·
oxygen sensors

CEL. Dealer said both upstream O2 sensors were bad. I can't tell any difference in performance.

The fan for the heat/AC does not work at any speed. That stopped about a week after the CEL came on.

Thanks for any helpful feedback.
 

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do the anti fouler trick

this should by you some time.

i just did this.
after fixing and relocating the knock sensor(50$) i started to have the p0420/p0430 codes.

i did some research on the net and found out about the antifoulers and spacing the o2 sensors out.

this is for the post o2 sensors not the pre's.

make sure the sensors are working first. use straightened out paper clips and back probe the connectors. take voltage readings and watch for voltage fluctuations. it is pretty easy.

this is a trick high performance guys use on thier exhaust.

the O2 sensor monitors the amount of oxygen in the exhaust stream. when the cats start to go bad then they cant clean the exhaust stream and the amount of oxygen goes up, which causes the o2 sensor to react. when it react too much it will throw codes.


if your having issues with the pre sensors, then i think the train of thought is what is going into or coming out of your engine. (bad spark causing incomplete firing, air intake leak somewhere, etc..)

post sensor failure means cats are bad or going bad. 8yr / 80k warranty on those i believe.

one sensor switches between voltages more than the other. i forget which one does but both should be in a range of .1-.9v

one will jump quickly between the range and the other will stay a little more steady. like i said its not hard to back probe the connectors and using a multimeter. also i can get you a factory repair/service manual if you want.

send me a private email.
 

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That sounds like a dealer price for parts and labor. I had a 02 CEL on my 02 Max when it had 22,000 miles on it. My gas mileage went way down in a hurry. Not sure what other effect it will have on your engine.
 

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That sounds like a dealer price for parts and labor. I had a 02 CEL on my 02 Max when it had 22,000 miles on it. My gas mileage went way down in a hurry. Not sure what other effect it will have on your engine.
well i know my truck isnt fixd.

this was only done in an effort to pass inspection and to remove the CEL.

it would not surprise me if it comes back on. BUT when i remove the secondaries i will need to use anti foulers to set things right.

and i still need to replace the primary cats and manifolds
 

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Discussion Starter · #7 ·
O2 sensors

Thanks, Zero and Massbaster. Definitely dealer price--and Ford dealer is closest to me. Nissan is 45 miles away. I spent three hours waiting for the diagnosis this morning.

I have a guy at a performance shop, and I'll take the truck over there next week. It's really a long turnaround time with him; that's why I did not start there.

I haven't been using premium gasoline, either.
 

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Thanks, Zero and Massbaster. Definitely dealer price--and Ford dealer is closest to me. Nissan is 45 miles away. I spent three hours waiting for the diagnosis this morning.

I have a guy at a performance shop, and I'll take the truck over there next week. It's really a long turnaround time with him; that's why I did not start there.

I haven't been using premium gasoline, either.
You're welcome. Doesn't a Supercharged Frontier require premium gas?
 

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Take it over to autozone and have them pull the codes for free. Then see what codes are the issue. You have 4 02 sensors. Dealer may just be saying you need both done for the $$$$.

Yes the Frontier needs premuium. I'll say this is that you probably also have a Knock Sensor issue too. However, getting it hooked up to the computer will show. If you have the KS issue you can replace if for around $600 at the dealer it will bring you better gas mileage and bring back the boost. The reason I am telling you this is because the KS is a failure and since you are a 2002 you are probably due for one.
 

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yes

it does require super unleaded.

it will run without it but you might have earlier knock sensor failure.

IMO even if you havent had a knock sensor failure yet, relocate anyways.


i have a 2004 s/c Lb cc. i also have a copy of the actual factory service manual. send me a private message if you want it,

i am not impressed as an owner nor as one who regurally works on my own vehicles. for atleast my model it really looks like this is the epitomy of over engineering and poor engineering on many levels.

alot of these issues could have been fixed or non existant, but they were either left there or designed to fail on purpose for the sake of maintenance and labor fees.

i have never been formally trained as a mechanic unless you count the 37 yrs i have had to pic my fathers master mechanic brain and of all the self taught repairs and info i gather for myself.

i guess as wild e. coyote would put it, self proclaiimed genius. (but still learning) nowadays with the advent of the internet, there really isnt anything you cant find or learn for your self or atleast get cheaper than at the stealer ship.

of course i will concede that in some rare instances the dealer may be the best choice.
 

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Go with these guys on here. Good rule of thumb, try out Auto Zone first always. I have a code reader here because I live in Germany and well... it's just better than going anywhere around here. My OBD II scanner was under $100. Another thing, if it is in fact your O2 sensors or really any sensor for that matter, just do it yourself. Like one said "Stealership", if you can play with Legos you can change an O2 sensor. Also, shop for your parts online. Nissan has Nissan Parts, NISMO and Nissan Accessories - Courtesyparts.com that will ship right to your door. I hope that you find what it is and best of luck. Take care.

Happy New Year,
-GT
 

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Discussion Starter · #12 ·
O2 sensors

Thanks to everyone! Yes, the owner's manual advises premium gas; also says you can use 87 octane with loss of performance. I've been wondering about the k/s for a long time. Since it can affect the O2 sensors, I'm thinking it's the root of the problem. No AutoZone here, either. A problem when you live in a small town and don't have mechanic's knowledge and skills. Maybe I can learn some. $600 for k/s plus $400 (or less) for O2 sensors plus new (rebuilt?) blower motor==I gotta get a loan.
 

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no need loan

just need alittle schooling, a haynes manual and this forum.

again even if the ks is good or bad, you should look into getting the maxima harness/KS and relocate it to one of the locations shown here.

all of theses components are easy to test with a mutlimeter AND it is all explained in the haynes manual as well as the factory service manual.

like i said, the ks will throw you in all different directions so make sure that gets fixed.

oh and one of those cheapy handheld OBD scanners is all you really need. i think they are around 80 bucks or so. as long as you can get the code, you can fix the truck,
 

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just picked up a bosch vehicle specific O2 sensor from autozone last week for less than $100. they are hard to get to, but easy to remove and install. busy an appropriate sized spark plug socket and take care of it yoursellf. O2 sensors monitor the byproducts produced in the exhasut and adjust full and air mixture as a result. you probably have noticed poor gas milieage.

i don't think a knock sensor will kill the O2 sensors. knock sensor codes are common on our vehicles n/a and s/c; and while they may lower your mpg a little, its not a big deal. they won't even throw the CEL. they are always showing a code, but as a "pending" code, thus not showing the light on the dash. its a good idea to fix, but i don't see how they would cause problems with the O2 sensors.

good luck wiht the fan problem!
 

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I have been very pleased with Spark plug, Spark plug wire, spark plug gap, spark plug cross reference and ignition wires at Sparkplugs.com and their OE equivalent O2 sensors. I would go with either NGK or Denso - about $60ea for the part. I would replace both banks, since a new one will be more sensitive than the old one and you'll get weird fuel mixture ratios left bank vs. right bank if you don't...

And to clear up some other misconceptions in this thread. You don't "wear out a knock sensor faster" by running regular fuel. The knock sensor is basically a microphone that listens for spark knock and reports it to the ECU so that it can retard the timing advance when it's detected. Heat kills the knock sensors, causing their cases to crack.

Heath
 

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I meant replacing both front (I guess that's what Ford calls upstream) sensors, left and right. All four is probably best, but the fronts are the ones that have more to do with engine control - specifically fuel mixture, and are the ones you worry about getting sluggish. The rears are just a check to make sure your cat. converters are functioning.

Heath
 

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just thought i would do this for fun

when i did the k/s relocate, i put the k/s on the supercharger. well that ended up going bad as well because i may have wired it wrong, ooops. so i returned it and got another one and made sure i had my wires correct and mounted it in the same spot on the s/c. i believe this location caused it to again go bad.

i had the 99 maxima harness and was getting the k/s's at aprox. 100$ each.
only paid for 2.

i decided to search for "vg33e knock sensors" and found one for 48. bucks. it matched up to an infiniti Q model car that had the same engine around 1999. (found a new location and been good ever since.)

soooo, i just did a search on "vg33e O2 sensors" and see them for alot of vehicles at 50$. just keep an eye out for the length of wire and you should be able to get for of them pretty cheap.
 

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I bet you were getting some weird noises for it to hear on the super charger! One of the experts on the early Q45 who is very knowledgable about the timing maps, and has unlimited acces to a Consult, tried a few things concerning the knock sensors. His conclusion was that the ECU not only checks to make sure it's seeing the proper resistance at start-up, but is also analyzing the information it's getting from the sensor at some point. Even with a good working sensor bolted to another area under the hood, the ECU would go back to it's safe timing map (as if the sensor had checked bad) in all cases except when the sensor was bolted to the correct place on the heads. If an OBDI ECU designed in 1988 (for his 1990 Q45) was able to do this - it's very likely that our smarter OBDII ECUs are even more sensitive.

Heath
 
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