# Help with clearing emission testing

**URL:** <https://community.cartalk.com/t/help-with-clearing-emission-testing/117334>\
**Category:** Maintenance/Repairs\
**Tags:** nissan, altima\
**Created:** [May 13, 2018, 11:21pm UTC](https://community.cartalk.com/t/help-with-clearing-emission-testing/117334 "2018-05-13T23:21:56Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![rsrvaltima](https://avatars.discourse-cdn.com/v4/letter/r/90ced4/32.png) [@rsrvaltima](https://community.cartalk.com/u/rsrvaltima)\
**Post date:** [May 13, 2018, 11:21pm UTC](https://community.cartalk.com/t/help-with-clearing-emission-testing/117334/1 "2018-05-13T23:21:56Z")

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Hi… I failed the emission test with a 2004 Nissan Altima in Illinois. Can someone help me with clearing the test?

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**Author:** ![db4690](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/db4690/32/2583_2.png) [@db4690](https://community.cartalk.com/u/db4690)\
**Post date:** [May 13, 2018, 11:55pm UTC](https://community.cartalk.com/t/help-with-clearing-emission-testing/117334/2 "2018-05-13T23:55:24Z")

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You’re going to have to give us considerably more information

I’ll assume your car was subject to only a plug-in test, not a dyno run, tailpipe test + plug-in test . . . ?

Why did the car fail?

Not enough readiness monitors were completed?

Check engine light failed to illuminate at key on, engine off?

Check engine light came on/remained on at idle?

If so, what were the codes . . . the failed test will usually include any fault codes which are commanding the check engine light to illuminate?

Tampering?

Missing emissions components?

I live in California and actually perform smog tests, but I’m not familiar with the regulations in Illinois. But I do know that procedures and regulations vary widely, depending on the state the car is registered in

Once you give us more information, I’ll try to help you, or somebody else will do so

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**Author:** ![jmcarc](https://avatars.discourse-cdn.com/v4/letter/j/278dde/32.png) [@jmcarc](https://community.cartalk.com/u/jmcarc)\
**Post date:** [May 14, 2018, 12:58am UTC](https://community.cartalk.com/t/help-with-clearing-emission-testing/117334/3 "2018-05-14T00:58:30Z")

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I can give you a number of possibilities:

dirty air filter  
worn spark plugs  
clogged fuel injectors - add a fuel injector cleaner to your gas tank.  
needs an oil change  
bad oxygen sensor  
clogged PCV valve

Your problem could be caused by any combination.

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**Author:** ![rsrvaltima](https://avatars.discourse-cdn.com/v4/letter/r/90ced4/32.png) [@rsrvaltima](https://community.cartalk.com/u/rsrvaltima)\
**Post date:** [May 14, 2018, 3:07am UTC](https://community.cartalk.com/t/help-with-clearing-emission-testing/117334/4 "2018-05-14T03:07:47Z")

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I had the P0420 cat converter going bad code on. I fixed it and i also replaced both the oxygen sensors. Now I get the P1273 code and i replaced the upstream oxygen sensor again. After couple of hours, the P1273 code is back.

Any suggestions on what could be going wrong? I used Bosch oxygen sensors and i heard that Bosch doesnt go well with Nissan engine, not sure if that is true though.

Any suggestion would really be heplful.

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<div class="post-metadata">

**Author:** ![db4690](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/db4690/32/2583_2.png) [@db4690](https://community.cartalk.com/u/db4690)\
**Post date:** [May 14, 2018, 3:28am UTC](https://community.cartalk.com/t/help-with-clearing-emission-testing/117334/5 "2018-05-14T03:28:38Z")

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> **[NTB04-126.pdf](https://www.autocodes.com/uploads/nissan/NTB04-126.pdf)**

Read that carefully

According to that document, if you replace the sensor without performing that reset procedure, the exact same code could reoccur. Did you perform the reset?

Clearing the code is not a reset . . . it’s only clearing the code, nothing more