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Toyota Repair/P0420 diagnostic code


I have a 1996 Toyota Camry with a 3.0 V6. The check engine light is on again. The catalytic converter was changed twice. The previous owner replaced it about a year ago. The car has 171,820 well maintained miles. I just had the converter changed again about two months ago.  The garage said that the one the previous owner installed was a cheaper inferior one.  They installed "a better quality" after-market converter after explaining the difference. Two of the oxygen sensors have been replaced.
 The engine, since a few weeks ago started using oil. The car could sit from just twenty five minutes to a cold first start of the day. Upon ignition, a puff of blue smoke emits from the tail pipe.  The smoke issue is intermittent, Could this cause the converter or sensors to fail? Or is the code something else?  Thank You

Hello, yes the excessive oil consumption can cause a converter to overheat and fail over time, the blue smoke on startup is common on these engines, usually caused by leaking valve stem seals, the seals can be replaced without removing the cylinder heads but at this mileage I would recommend removing the heads and doing a complete valve job, some V6 engines also have a tendency to develop excessive sludge or oil gelling, it can be inspected for this by removing the front accessible valve cover.

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Ted Ritter


I have more than 28 years experience as toyota technician, I will be able to answer most questions related to the Toyota product line up to the present year models,I am located in the US but welcome questions from other regions of the world. When asking a question please provide specific information: year,model, engine,transmission information. Provide as much information as possible including a brief repair history if possible. I have been a volunteer here for more ten years an have answered over 16,000 questions helping Toyota owners with their problems and save thousands of dollars without any compensation, some of my answers are published on many other websites including google and various automotive forums. DONATIONS ARE VERY MUCH APPRECIATED, IF YOU HAVE RECIEVED HELPFUL INFORMATION PLEASE MAKE A DONATION. AS OF TODAY (JULY 22, 2014) ALL REQUESTED GRAPHICS, ILLUSTRATIONS, DIAGRAMS, PHOTOS, WILL REQUIRE THE MINUMUM DONATION UP FRONT.


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