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Bad catalytic?

4K views 6 replies 3 participants last post by  rk_classic 
#1 ·
Is there any way to find which catalytic converter is bad? Besides cutting them off and looking inside?
The code p0420 came up and also had some rattling but then it all went away. I do have vibrations once I accelerate pass 25mph and up along with a humm also gas mpg is going down. It does get louder and vibrations get worse on the highways
It's a 2003 2.4L with 149,XXX
 
#2 ·
P0420 is Bank 1, the front Pre-Cat. P0430 is for the rear Pre-Cat. Code is for Catalytic Converter Efficiency, so either your front Pre Cat is going bad or the sensors upstream and down stream are going bad.
 
#4 ·
When mine went bad (2.5) the jeep would only idle and I could not accelerate over 5 mph it was plugged big time with no codes. The only noise I would hear was a rattle that I thought was the muffler but turned out to be the insides of the converter. You can take off your skid plate and hit the bottom of the converter with your fist to see if you hear any of the honeycomb bouncing around.
 
#5 ·
Which catalytic was bad? About a month ago I took it to a muffler shop and the guy shook it while the Jeep was up on the lift. There was no rattle.
I could drive on the highways with no problem. Only thing that is bothering me is knowing that I did have the code and also the rattle but now I have the vibrations. Not knowing what's causing that is getting to me.
 
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