passing emissions


Asked by Apr 22, 2014 at 10:53 PM about the 2006 Hyundai Tucson Limited 2WD

Question type: Maintenance & Repair

I have a 6 cylinder Hyundai Tucson 2WD with about 123,000 miles.  I change the oil
regularly and had the appropriate serve done at about 65,000.  Now, however is will not
pass the state of MD emissions.  The diagnostic trouble codes are

KOER Result failed
MIL command status failed

Does anyone have any suggestions as to what this can be besides an entire $1600
replacement of the front catalytic converter?

Thanks so much
E. Carter

4 Answers


1 out of 1 people think this is helpful.
99,525 -- possibly o2 sensor bad, bad cat or exhaust leak

2 out of 2 people think this is helpful.
Best Answer
James Ramond

That's a puzzle, how does two cats go bad together, did you put an additive in the tank and melt the cores? was it running a misfire for the last year killing the cat.? go to parts and get a o2 bung extension for a side and it backs the rear sensor more away and fools it to thinking the core is cleaning things up, it cant get a good wiff of the passing carbons from an inoperable core. if results happen do the other side as you somehow got two


Many techs go to the sensors first and then check for exhaust or intake leaks and general condition of tune. This doesn't always result in solving issue. The manual suggests 5 different causes. Three have been mentioned already, other possibles are vapor cannister related and last one is possible ecm reflash due to age and miles. Smog techs that seem to know what they are doing many times suggest an ecm update to correct out of range parameters. Remember this if a po 430 and 420 code pops up together or one first then the other this doesn't mean their plugged, it means something is making them operate inefficiently.

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