code p0420 and p0430

2003 TOYOTA 4RUNNER
208,000 MILES
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LFLEMING2
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Engine light came on and car started running very rough. Was low on oil. Had oil changed and fuel system flushed. Car ran for 1 day and light came back on. Took back and they said both cat/cons wer bad. Do they both go bad at the same time or could they have flushed someting into them or the o2 sensors?
Sep 6, 2012 at 5:40 PM
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SATURNTECH9
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What kind of watch was done? Also what size engine do you have?
Sep 6, 2012 at 6:25 PM
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LFLEMING2
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I don't understand watch? It is a V6
Sep 6, 2012 at 7:33 PM
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SATURNTECH9
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Sorry I was asking what kind of fuel system flush was done? So where these codes active before the fuel system flush? If not how long after the fuel system flush were the codes active?
Sep 6, 2012 at 8:11 PM
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LFLEMING2
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The entire fuel injection and all filters were cleaned or changed. The codes came up the next day. have been on for a while.
Sep 6, 2012 at 8:18 PM
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SATURNTECH9
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You have to check for exhaust leaks then check the o2 sensors and if all that is good then bad cats.It sounds like the cleaning took out the cats or the sensors though if you never had the codes before.
Sep 6, 2012 at 8:37 PM
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KHLOW2008
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When engine runs with misfires, they can take out the catalytic converters due to unburnt fuel getting to them. They would overheat and glow red as they try to burn off the excess fuel and over period of time they would fail.

Just make sure you have the engine running well before you atttempt replacing the catalytic converters if required. Failure to do so would damage the new catalytic converters as well.
Sep 7, 2012 at 1:26 AM
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