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Q: Catalytic Converter Replacement - 2001 Lexus IS300.

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Good afternoon Your Mechanic Community - I have a 2001 Lexus IS300, it has 182K miles, and I am the original owner. The 2001 IS300 drive well and I have done all the key maintenance for the car. Overall it is great shape, but like with any older car there are times when an old part will need to be changed.
In this case, its the catalytic converter. Recently the check engine light came on and the service shop found “Code p0420 catalyst system efficiency below threshold bank 1”. I was told I would need to get a new catalytic converter.
I am looking forward to working with Your Mechanic in replacing the catalytic converter. In advance of my appointment next Saturday (02/25) and knowing this is a critical job with catalytic converter being connected to the Emissions Testing in Virginia.

-For the mechanics online who have worked Lexus IS300 cars, are there any tips and key items to look out for in replacing the catalytic converter? Also, is there a way to check it passes emission?

My car has 1820000 miles.
My car has an automatic transmission.

Hi there. Before you decide to have the catalytic converter replaced in your vehicle, consider performing the following checks:

Check the following:

  • A damaged or failed oxygen sensor
  • The oxygen sensor wiring damaged or connected improperly
  • The engine coolant temperature sensor is not working properly
  • A leaking exhaust manifold or a leak in the exhaust system
  • The spark timing is retarded
  • There is a leaking fuel injector or there is high fuel pressure
  • The engine has a cylinder misfire
  • The engine oil is contaminated

If all of the above areas are checked and passes their functions and conditions, then the catalytic converter would need replaced. If you need further assistance with your P0420 code, then seek out a professional, such as one from Your Mechanic, to help you.

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