Failed smog due to check engine light not cycling but turns on for codes

2004 Hyundai Sonata Nevada smog failed due to check engine light not cycling when you turn the key to on position without starting it but the check engine light came on a week later due to the mass airflow sensor coming unplugged, in Nevada I have to have the car repaired at a 2 G authorized shop and I don’t want to pay for diagnosis I’d rather bring the car in knowing what the problem is does anybody have any ideas

Sometimes, if you remove the negative battery cable and leave it off overnight it might reset your CEL.

The Check Engine light coming on when the ignition switch is in the run position is the self-test for the computer.

If the CEL isn’t coming on, it means the computer isn’t grounding self-test circuit. So the computer may be bad.


That’s also going to reset all the readiness monitors

deleted :stuck_out_tongue_winking_eye:

THIS is why I prefer vehicles from 1995 and older–none of this “computer not ready” preventing a successful emission test BS. For model year 1995 and older, nothing is connected to the onboard computer, no codes are checked, and the presence or absence of warning lights makes no difference–all that matters is the actual pollutant levels, which is how it should be.

I see cars for sale all the time, which run fine–and are probably not polluting any more than normal–but won’t pass emissions due to “monitors not ready” that will never become ready or CEL on for “phantom codes” that cannot be reset. On an older car, spending $1000 or more to replace a PCM if one is even available is often out of the question, so off to the junkyard or on to Craigslist as a “mechanic special”.

At least here, most counties do not require emission testing, so people who happen to live outside of the emission testing zone can get amazing deals on cars which run fine, but would not pass due to computer/wiring harness problems.

If things went back to the way you described . . . smog inspections would be costlier, and they would take a LOT longer

There would be no such thing as a “quickie smog”

although I suspect you would be willing to tolerate that . . . I suspect society as a whole would not be ready to take such a step backward.

Pay more more money AND wait longer . . . sounds like a sure-fire winner, right? :stuck_out_tongue_winking_eye:

And by the way, the pre-1995 smog inspection check list has a LOT more things on it

I’m really not making this stuff up, when I say it would take a lot longer