Help with "check engine"

[noxiousCaitSith]

my check engine light has been on since i bought my explorer... i don't think there was really anything seriously wrong with it, but my grandpa wanted to check it just to make sure. he used a trouble code reader (Creader) and got 2 codes. one was "catalyst system efficiency below threshold (bank 1)"
and i have no idea what it means. the other was "evaporative emission control system leak (gross leak)".

if anyone can help me out as to what these mean, i would appreciate it.

 

[Blee1099]

my check engine light has been on since i bought my explorer... i don't think there was really anything seriously wrong with it, but my grandpa wanted to check it just to make sure. he used a trouble code reader (Creader) and got 2 codes. one was "catalyst system efficiency below threshold (bank 1)"
and i have no idea what it means. the other was "evaporative emission control system leak (gross leak)".

if anyone can help me out as to what these mean, i would appreciate it.

Welcome to the site.. Do you remember what particular codes it was? Its really hard to pinpoint what the cause can be. It could be bad 02 sensors, dirty MAF, EGR valve, etc. If you have an Autozone near you, get your truck scanned for codes again and post what the codes # were (Its free at Autozone). They should be something like P0174 or any thing with P0###.

 

[noxiousCaitSith]

oh yeah...

they are 0420 and 0455, respectively.

but there weren't any letters. the reader only shows 4 numbers.

 

[Glacier991]

the gross leak is just an indication that somewhere in the fuel storage system, there is a breach of vapor (air-tight) integrity.. over .030 inches in dia. Often that is a cap. Not a biggie. Don't sweat it. Let me check the other.... I don;t think the code you gave matches the description (much as I work with codes I still don't remember them all... but do not recall a 400 series code being Cat efficiency)

[edit. I am going to leave the above, just to show how dumb I can be. Yes the 0420 code IS as he says! Cat efficiency bank 1.]

Cat efficiency is measured by having the computer enrichen and lean out the mixture during a test cycle. The 02 sensor in front of the cat shoud jump around when the computer does this. The "after CAT" sensor should stay constant, since the cat should "dispose" of the excess on the rich cycle. If the CAT ALSO moves... there is a suggestion that the CAT is not doing it's job properly, and is "below efficent operation".

You will probably need to fix this before your next smog check... but for now, short term, it too is probably ok.