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Have the misfires and other codes cleared? If not, they can trigger a cat code, but the code is from the opposite side of the misfires.
Check the flex pipe for leaks, as it will trigger a cat code. Scan the O2 sensor readouts with VCDS.
 

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Discussion Starter #22
  1. The misfire codes are gone after doing the timing belt and cam and crank sensor along with the Serpentine belt. The codes I have now are 17801, 17802, 17803 and this new one P0431 which popped on out of nowhere after driving around the car a little to test drive it some.
 

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Discussion Starter #23
O and a update I charged the battery and now it doesn't seem to be going out anymore its holding its charge because I had to leave the car sitting and didn't start it for 3 days but when I did go out to start it after the 3 days expecting it wouldnt start it fired right up. I haven't been able to check the voltage its putting out though as someone probably my brother stole my voltage meter or whatever it's called
 

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Not Necessarily, I have seen this code clear up after the misfires were fixed. Unburned gas is being dumped into the cat every time it misfires and can cause the sensors to give false readings, the battery dying or have low voltage on these car can cause all kinds of weird problems. I would also look into the pcv system, this was the cause of multiple misfires on my car.
Good luck!
 

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My bad. Somehow I over looked that the misfires had cleared up, but definitely look into the battery, because it can cause some very weird problems with these cars
 

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You certainly didn't go wrong with getting the timing belt and related parts replaced. Sounds like you averted a ticking time bomb having it done. As others mentioned. Get the battery load tested to check it's overall condition to rule a weak batt to rule that out.
 

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The Cat code might be resulting from insufficient 'secondary air' from the SAI pump and valves, although the Cats are no doubt quite well used by now.
 
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