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Dan, Technician
Category: Car
Satisfied Customers: 23485
Experience:  Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Database
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2002 daewoo nubira trouble code 420

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2002 daewoo nubira trouble code 420
Welcome to JustAnswer, my name is XXXXX XXXXX I'm here to help get your problem resolved. Did you use a OEM catalytic converter or aftermarket converter? Thanks
Customer: replied 3 years ago.

I used a 50 states magnaflow. Also I remembered the first cause of getting this cause was a vacuum leek. corrected this and itn it's been 2 weeks without any codes. was throwing me also a 320 code. we corrected. and when we tried to pass smog test. I was told it did not turn 2 monitors to run it. also has a brand new timing belt, tensioner bearing and water pump. this last just for maintanence pourpuses. also I tuned thje engine. the only thing not replaced is the oxygen sensor, as my friends scanner, a matco, told me it was between normal parameters.

This code almost always means the catalytic converter has failed and they have a lot of problems with aftermarket catalytic converters. The only possible things this code can mean is exhaust leak, failed catalytic converter, or oxygen sensors and it is the converter 95% of the time. If the oxygen sensors are working correctly and there are no exhaust leaks I would either try another brand catalytic converter or replace with a OEM. I am sorry there is not a cheaper fix, please do not leave me a negative rating for the bad news. Let m know if you have questions or if you would like me to open question back up so you can get another opinion. Thanks
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