# Failed Emission Test due to o2 sensor - NEEP YOUR HELP



## Purple B14 (Dec 13, 2002)

Well, I really don't want this happen to any of you. But shit happened to me this morning. I need help, please !

I faild the "Oxides of Nitrogen" test. The result was more than double of the passing level. I asked a local mechanic, and was told it's the o2 sensor problem.

I had my HS header installed in April 03', and EGR tube & o2 sensor were also installed properly. Since it's the problem with o2 sensor, it shoul comes from either the one on header, or the other one on cat.

Also, my check engine light is on for almost 3 years. *Right now, I need to know which o2 sensor is the bitch !* I have the following choices,

(1) Take car back to dealer, and have them run test on the check engine light. This will probably tells me the problem. Costs $84. ( Do you know any place other than dealer who can run the test ?? )

(2) Go ahead and replace these o2 sensors. They are expensive !!

(3) Your suggestion .....

This is really a lot of headache !! Please help me out !! I appreciate any opinion !

Michael


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## NissanGirl2ooSX (Mar 15, 2004)

Purple B14 said:


> Well, I really don't want this happen to any of you. But shit happened to me this morning. I need help, please !
> 
> I faild the "Oxides of Nitrogen" test. The result was more than double of the passing level. I asked a local mechanic, and was told it's the o2 sensor problem.
> 
> ...


Could be the one underneath the cat..since you did change the one in the front then that just leaves the back. Well over at my store diagnostics cost 79$ so not much of a difference, I dont know of any other place that does it cheaper..you could try AutoZone though if you have one around your area. 

I had the same problem with my sensors..they were never changed for about 95,000 miles so they were bound to mess up. Yea o2 sensors suck..but once they are in and that annoying light comes off its all worth it I guess haha.


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## chimmike (Oct 17, 2002)

you're not gonna pass an emissions test with an aftermarket header in dude.........it eliminates a precat in the stock header and that leaves more pollutants in the exhaust.


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## aminidab (Apr 30, 2002)

You can pull the engine code without any tools, you just have to turn a screw on the ECU. Try searching or check here http://www.nissanforums.com/showthread.php?t=43446&highlight=check+CEL

That should tell you which sensor is having the problem.

The header doesn't necessarily eliminate a cat. Not all B14s have a cat built into the stock manifold, the 95-97 federal ones don't I believe.


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## Jeb D. (Jun 24, 2004)

Also, Autozone runs the diagnostic for free. Always.


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## aggrivator (Feb 12, 2004)

i think shucks/kragen/checkers does too, and they sell the reader for under $100. i bought one for all by b14 problems, now all my friends want the hookup, so they bring lunch or a half rack they can use it all they want that day... :cheers:


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## Nico Flax (May 3, 2003)

Don't worry about emissions with a header, I passed easily and my car kinda tricked out, I'm sure you'll be able to pass.


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## Purple B14 (Dec 13, 2002)

I really appreciate all your help, brothers.

Well, I chatted with two friends in my local area. One had a Type-R, and he couldn't pass that damn emission test with aftermarket header as well. What he did was put stock header and mid-pipe to pass that thing.

Another friend owns a 99 Maxima with aftermarket down pipe and no pre-cat. He barely passed that test. 

So this is realy getting me confused. What I am going to do now is to run the ECU test to find out what's wrong. Fix it and run engine on highway for an hour, then do the emission test again.

If everything fails, I will be left with no choice except to put on stock header. Damn this emission thing !

But still, let me know if you have some thoughts !

Michael


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## Neil (Aug 13, 2002)

Are you in california or some strict emissions and smog state?


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## jer28 (Jan 20, 2003)

I came close regarding passing the emissions testing. CA and MA are about the same strictness. I think there are a few other states now with the enhanced emissions tests.

I would find the offending o2 sensor (its probally not both). There are threads on how to test the sensor voltages when the car is running. Fix the sensor then drive the car so its nice and hot. You'll pass, it takes a car in terrible shape to fail. I had an old car parked for a year with the same gas, drove 5 miles (slow 30-40 mph driving) to the testing garage and still passed. I find it hard to believe that your car won't pass (once you fix a bad sensor).


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## Purple B14 (Dec 13, 2002)

Well, I actually too the car for an ECU test last night. It read a o2 sensor problem, just like we all predicted. However, it only says "B1S1 O2 sensor", but doesn't tell me which. I am going to replace both of them, regardless. Just to avoid future headaches.

Yes, replace the sensor, and run the car til it's all warmed up. Then do the test. I should pass ( god bless ). 

Just for reference, mine is 95 1.6 Sentra with GA16DE in Vancouver, BC. The header has NO pre-cat since it's merely a pipe. Since it has no pre-cat, a HS header with proper EGR and O2 sensor should pass the test.

I will update on how it goes. Hopefully this can help other members in the future.

Michael


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## payk (May 5, 2004)

the rear 02 sensor is heated so the daignostics would read H02 sensor so it is probably the front one. also the cat tends to be worn out faster if the car is modified so you might want to have that checked random tech has a cat for around 99 OEM cats dont last too long about 6 yrs


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