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Ron Z.
Ron Z., - Toyota Tech -
Category: Toyota
Satisfied Customers: 18775
Experience:  18+yrs experience. State Inspector and Toyota Diagnostics
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I have a obd code of 0420 is bank1 before or after the cat

Customer Question

I have a obd code of 0420 is bank1 before or after the cat?
Submitted: 2 years ago.
Category: Toyota
Expert:  Ron Z. replied 2 years ago.
Hello! Welcome to the site! Thanks for coming! I'm Ron Z. I'm here to provide as much information and insight as I can, to best answer your question.
May I have the year, model and engine size of this Toyota?
Customer: replied 2 years ago.
01 Toyota rav 4 4L 4cyc
Customer: replied 2 years ago.
2.0L
Expert:  Ron Z. replied 2 years ago.
Great, thanks!
Unfortunately, the P0420 is a fairly straight forward code, and a fairly common problem. This code points to a failing Catalytic Converter. The Oxygen Sensors measure the amount of emissions in the exhaust going into, and then out of the converter. When they see that the converter is not "cleaning" the exhaust enough to meet specs, the Converter is deemed "below threshold" and the P0420 is set. Make sure there are no current cylinder misfires. Make sure there are no leaks in the exhaust system. Which, if there were, you should be able to hear. Sounding like a repeating "tick" or "puff" from the exhaust. Usually more predominate when the engine is cold. Make sure to include the exhaust manifold when checking for leaks/cracks. If these check ok, then most commonly, the Converter is "on it's way out" and will need replacement in the near future. Keep in mind, you will need a replacement converter that meets specs. Those "universal" or "discount" converters sold at some after market parts stores do not meet specs, and will not cure a P0420. On this vehicle, the Converter is built into and part of the Exhaust Manifold. So if hte replacement Converter needs to have the old one "cut out" and the new one "welded in place" - this is the wrong converter and will not solve the problem. Please remember to do the right thing and leave a rating using the stars at the top right of this page or accept the answer so I may be credited for this Q&A! You can ask follow-up questions even after you rate or accept. If you cannot rate or accept, please reply and let me know!