Question about 2005 Toyota Corolla

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Check engine light - P0420 code

I have a 98 Corolla. About a month back the check engine light came on. I took it AutoZone and they pulled out P0420 code. I took it to an exhaust place where they said the Catalytic converter needed to be replaced. I got it done and paid $190 for it. The light came on again. I believe it would be about 50 miles or so after which the light would come on again if the problem is still there. Had it diagnosed at Autozone and Advance Auto Parts to make sure it was the same code. It was the same P0420 code. Took it back to the same shop and after re-diagnosis he told me both the main and the rear oxygen sensor are faulty. He is charging $420 for it. Any advice on what i should do? Is that a reasonable price? How long can i push with out getting it fixed( i know i needs to be fixed for emissions, but there is still time)?I have heard the computer spits out a different code if the main O2 sensor is bad? I am confused...Need help...

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Causes A code P0420 may mean that one or more of the following has happened:

  • Leaded fuel was used where unleaded was called for
  • An oxygen sensor is not reading (functioning) properly
  • The engine coolant temperature sensor is not working properly
  • Damaged or leaking exhaust manifold / catalytic converter / exhaust pipe
  • Retarded spark timing
  • The oxygen sensors in front and behind the converter are reporting too similar of readings
Robert

Please rate this solution thanks

Posted on Feb 02, 2009

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Yeah, get the codes. Stop by Autozone. Better yet, pick up a scanner so you can read them at your leisure. I have an OBD II scanner that looks like this:
http://www.fcardiagnostictools.com/obd2/1-f3-w-world-cars.html
It gets you the codes.

Posted on Dec 03, 2012

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Hi

The trouble areas associated with this code are as follows:
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The idea is to check for exhaust leaks first then the front sensor and rear sensor. If these all check out then the cat needs to be replaced.

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