99 Es300 P0420 Code - ClubLexus - Lexus Forum Discussion

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99 Es300 P0420 Code

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Old 05-30-09, 03:54 PM   #1
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Default 99 Es300 P0420 Code


Got a 130K miles 99 Es300 Lexus from a local dealer last week, since there was some noise coming from the exhaust the dealer had cut the pipes right in front of the CAT and replaced with some after market ones and he also showed me the CAT, saying its clean and wont need replacement.

I took it for emissions testing and it passed without any problems. BUT, yesterday night the VSC, Check Engine and VSC off light came on and for the past 2 days there has been some surge in rpm at low speeds and at times some stalling. When I took to Autozone they said 2 same codes P0420 The guy suggested it might be cause of the CAT, or ignition system or the fuel system problem. Then took to the lexus dealer and after checking they said it because of the CAT, but said since the dealer had fixed after market pipes cannot replace the CAT alone and came with an estimate of $3500 saying the whole exhaust has to be replaced. As for the ignition said the surges was because of some leak in the hose and I have ordered for a new one .

I dont understand just yesterday it passed the emissions n the CAT seemed clean enough when the dealer showed, so have reset the codes and hopefully it wont come back again.

Please help me out, can the CAT fail so soon ????? and cant I ask a local mechanic to fix the CAT alone if necessary instead of the entire system ????


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Old 05-31-09, 01:41 AM   #2
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Your post if very confusing. Are you saying that you had a exhaust leak, and the dealer replaced sections of the pipe before the cat?

You say that Autozone said you had 2 same codes P0420????

And ignition / surges and leak in hoses. If you are talking about intake hoses and a possible vac leak, then this could also be the cause of the p0420. Fix this first and get the engine running properly.

Lastly, are you saying that you purchased the car from a dealer, and at the time of the purchase it had a audible exhaust leak, which they repaired. And then a short time later you brought the car back to the dealer, and they wanted to replace the exhaust system for $3500?? I would have only one thing to say about that,,Find a good mechanic, cause that dealer sounds like a rip off.
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