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P0420 bank 1. 06 malibu maxx 3.5. Checked for exhaust leaks…

P0420 bank 1 Mechanic's...

P0420 bank 1

Mechanic's Assistant: What is the model/year of your Chevy?

06 malibu maxx 3.5

Mechanic's Assistant: Are you fixing your Malibu Maxx yourself? What have you tried so far?

Checked for exhaust leaks sprayed around intake looking for vaccume leakes

Mechanic's Assistant: How old are the hoses? And what driving conditions do you most often encounter?

In town driving hoses are in good shape

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Answered in 1 minute by:
10/13/2017
Ron Z.
Ron Z., - Chevy Tech -
Category: Chevy
Satisfied Customers: 20,060
Experience: 18+yrs experience. State Inspector and Chevy Diagnostics
Verified

Hi! Welcome to JustAnswer. Thanks for coming! I'm Ron and I'll be working with you on your question today.

Can you tell me roughly how many miles are on this vehicle?

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Customer reply replied 10 months ago
173000

Great. Thank-you. Please give me one moment to type out some info for you. Sit tight one minute... I'll be right back!

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Thanks for holding!

Unfortunately, the P0420 is a fairly straight forward code, and a fairly common problem. This code points to a failing Catalytic Converter for Bank1 (the side of the engine closest to the windshield). 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 prodominate 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. Please be kind enough to leave a rating for our Q&A using the 'stars' at the top of the page or click 'Accept' when I have answered all your questions. A 5-star rating is very much appreciated! Rating or accepting my answer does not cost you extra.

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Were there any other questions I could help you with today?

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Customer reply replied 10 months ago
What about putting an antifouler in the bank one o2 to get it through inspection

This will not cure the P0420. The converter is not cleaning the exhaust to meet specs. If you put this in place of the oxygen sensor, the system will set a faulty oxygen sensor code as well as the P0420. Sorry to be the bearer of bad news here, but unfortunately, the cure is going to be to replace the Converter.

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Were there any other questions I could help you with today?

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Customer reply replied 10 months ago
No thanks for the help

You're welcome! Glad I could be of some help today! Please remember to leave a rating for our Q&A using the stars at the top of the page! Have a great weekend!

Ron Z.
Ron Z., - Chevy Tech -
Category: Chevy
Satisfied Customers: 20,060
Experience: 18+yrs experience. State Inspector and Chevy Diagnostics
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