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catalyst

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double_u_4

Veteran CEG'er
Joined
Oct 7, 2009
Messages
897
Location
romeoville, il
my CEL came on & i tested it & it came up with the P0420 code. saying calalyst effiency low bank 1. is this meaning i need a new catalytic converter. if so which 1 do i need. i tried looking 1 up but its shows a couple different kinds.
 
It means you should search "0420" in the troubleshooting forum and do some reading. Some very easy and cheap fixes versus getting new cats....
 
Cat efficiency low could be caused by quite a few things, Malfunction Indicator Light (MIL) eliminators are mainly used for when you remove the cats (either gutted or headers) and they just fool the system into thinking the cats are running right, the PCM checks the upper oxygen sensors for what is coming out of the engine to check AF ratio and other things, the bottom oxygen sensors are just a check to see what's coming out of the cat to confirm they are scrubbing the exhaust like they should.

The code your getting, could just be junk, first thing to do is clear it (either unplug negative battery cable for a minute, or erase it with a code scanner) and then just drive it to see if it comes back on. Since you're not pulling an O2 code as well, I wouldn't look at those yet, but it might be a good idea to do a tune up if you haven't in a while. A lot of times when that's the only code pulled though, it's a garbage code and once erased will not return.
 
ya i reset & it hasnt came back on yet. i changed my O 2's about 6 months ago along with plugs n wires. i probably should change the fuel filter thou. il just have to wait n see i f it comes back on
 
Keep in mind that I seem to recall a couple people in the years I've been on here complaining about this code never going away, some of them throwing tons of money and finding nothing wrong, it would just always come back on.
 
Well I'm not saying that will be for sure your issue, and more than likely there is an issue with those cars of some sort, just letting you know there have been reports of p0420 codes appearing for an unexplained reason, again, it's more than likely that there was a problem that was just not found, or it got fixed eventually and they simply never posted the cause. Regardless, if it continues to appear a new fuel filter would be helpful (probably would be anyway) or other cheap checks such as spraying carb cleaner to locate a vacuum leak, but for now, if it's not on and the car runs fine, I wouldn't be too concerned with it. Good luck!
 
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