Do I need to clear codes to get vehicle through emissions?

[ArizonaJon]

My 98 Ford Taurus SE had a check engine soon light come on. I took it to a Ford Dealer and they told me the problem was the oxygen sensor that is before the catylytic converter. The Ford Dealer wanted $400 to do the repair so I went to an Auto Zone and purchased the oxygen sensor for $65.00. Auto Zone even lent me the special oxygen sensor tool to intall and remove the sensor. It was pretty easy to do. I could not believe a garage would get $400.00 to do what I did.

The check engine soon light has went off. The car seems to be working wonderfully. I am aware though that the computer on a car stores these codes. I am aware that stored codes can be in the computer even when the light is not on. What I am concerned about is getting the car through emmissions next January. Here in Arizona the emissions testing people hook their equipment into the OBD II socket and look for codes. I am not sure if they look for stored codes or active codes only. I am concerned that this code will still be stored in there from when the vehicle was not working and it will show them a "false test" because I have already made the repairs myself.

Is this something I need to be concerned about? If it is, is there a way to erase all stored codes in the car's computer since I do not have the OBD II scanning equipment? Any help will be appreciated.

[97taurusdude]

I wouldn't think you have anything to worry about, don't think it's against the law to do work on your own car, sounds like you fixed the problem yourself. If they can detect you disconnected the battery just tell them it went dead and you took it in to get charged.

[TomV]

ArizonaJon, Relax!

Only the active codes are used to determine the pass/fail criteria. If old codes were used then most older cars would never pass.

[mcconnc]

If you are worried about any codes coming up, go to a place like Auto Zone or Advanced Auto Parts and they will let you use their diagnostic computer and give you any codes that come up. You can also use that computer to clear the codes.

[Robert1010]

I'm a instuctor for another state emission test program. We only look for stored DTC's (trouble codes) if the MIL lamp (check engine lamp) is on or commanded on by the computer. BUT we do check to see if all the diagnostic monitors have run. If you erase all stored codes or disconnect the battery, all info is cleared. You will fail the emission test for the car not being ready to test. You will have to drive the car till all of the diagnostic monitors have run--100-200 miles. There are some exceptions to what I said. That is why the inspector class is 16 hours long.

The short answer don't do anything, you have repaired the car! That is what the EPA cares about.

Rob

[fuba]

My 96 did the same thing. I replaced the 02's and it passed.