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'02 Nissan Altima smog fail and high idle rpm

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New User

Mar 15, 2010, 11:43 AM

Post #1 of 3 (2625 views)
'02 Nissan Altima smog fail and high idle rpm Sign In

2002 Nissan Altima 2.5
91000 miles

Recently failed smog test. Passed visual, Passed Emissions. But failed the functional check: This vehicle failed the MIL/Check Engine Light Test due to failure to successfully complete all OBD self tests.

Now I did just pick up my car from my mechanic that afternoon before the smog test because he had been fixing a leak from the timing cover. Would that job require the battery to be disconnected causing the memory system to reset?

Well, the smog tech told me to drive it 50 miles or so and then re-test. The check engine light is not on and i'm over the 50 miles.

But before I bring it in again, the smog tech also told me that the idle rpm was 1300. He said it should be 900 rpm. What could be causing this high idle ... and more importantly, for the time being, will the high idle cause me to fail the smog, even though I did pass emissons and my service engine soon light is not on?

steve01832 profile image

Mar 15, 2010, 5:09 PM

Post #2 of 3 (2617 views)
Re: '02 Nissan Altima smog fail and high idle rpm Sign In

Every state has its own rules and regulations when it comes to I/M testing. Here in MASS, our emissions test only consists of the inspector plugging a scan tool in and checking for codes. Depending on where you live will depend on what kind of emissions test is performed.


Loren Champlain Sr
Veteran / Moderator
Loren Champlain Sr profile image

Mar 16, 2010, 5:07 PM

Post #3 of 3 (2606 views)
Re: '02 Nissan Altima smog fail and high idle rpm Sign In

cherub; Yes, disconnecting the battery can erase the KAM (keep alive memory). It is very similar to your PC at home. When you turn it on, it goes through several 'checks' before you can start using it. The PCM in your car does the same thing, but takes longer. Usually, two drive cycles. When we 'clear codes', we will attempt to drive the vehicle far enough so that the readiness monitors have completed prior to giving it back to the customer. Note, I said attempt. Some times, it can take several trips. This is so that the PCM can 'relearn' stratedgies. In WA state, the idle speed must be below 1100rpm to test. If your idle doesn't return to normal, have your mechanic check for a vacuum leak, or minimum idle adjustment.
SW Washington

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