Code P0420 and P0430

Tiny
LFLEMING2
  • MEMBER
  • 2003 TOYOTA 4RUNNER
  • 208,000 MILES
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?
Thursday, September 6th, 2012 AT 5:40 PM

6 Replies

Tiny
SATURNTECH9
  • MECHANIC
  • 30,869 POSTS
What kind of watch was done? Also what size engine do you have?
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Thursday, September 6th, 2012 AT 6:25 PM
Tiny
LFLEMING2
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  • 3 POSTS
I don't understand watch? It is a V6
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Thursday, September 6th, 2012 AT 7:33 PM
Tiny
SATURNTECH9
  • MECHANIC
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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?
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Thursday, September 6th, 2012 AT 8:11 PM
Tiny
LFLEMING2
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  • 3 POSTS
The entire fuel injection and all filters were cleaned or changed. The codes came up the next day. Have been on for a while.
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Thursday, September 6th, 2012 AT 8:18 PM
Tiny
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.
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Thursday, September 6th, 2012 AT 8:37 PM
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
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.
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Friday, September 7th, 2012 AT 1:26 AM

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