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Getting engine light and code p0420, 224k miles on 2003

Getting engine light and...

Getting engine light and code p0420, 224k miles on 2003 corolle ce

Mechanic's Assistant: Has your vehicle stalled? Has anyone run a diagnostic test to pull the trouble code?

I did, code was p0420....sensor o2 bank 1 volts are from .2 to .7 when warmed up, problem looks like the bank 1 sensor 2 is not flat lining., do I have the sensors right, sensor 1 is before the cat convertor and sensor 2 is after the cat convertor?

Mechanic's Assistant: What is the model of your '03 Toyota?

corolla ce

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

Bought a sensor data logger and plugged into the obd2 diagnostic port, did onboard trends, can you tell me where sensor 1 and sensor 2 is located?

Mechanic's Assistant: Anything else you want the mechanic to know before I connect you?

Tell them that the voltage trends from sensor 1 and sensor 2 are almost identical, thanks.

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Answered in 1 minute by:
3/20/2018
carguy1
carguy1, auto technician
Category: Toyota
Satisfied Customers: 27,749
Experience: 25 Years experience all makes and models.Nissan factory trained,Certified Subaru Tech
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You do have your sensors correct, sensor one is before, sensor 2 is after. If both sensors basically mimic each other, it means the converter isn't doing it's job. You should see quick changes in the front sensor and then slower more rhythmic changes to the rear sensor. Kind of like a rolling wave pattern. It sounds like you need a new catalytic converter to be honest.

Please let me know if there is anything else I can do to help.
Just Answer does not compensate me for my time and resources, you do when you rate my answer by using the stars at the top of the page. Payment for your question includes any follow-up questions you may have. Free trials and subscription questions still require ratings. Your question does not close after you rate. You will still be able to contact me by replying to this post.
Thank you so much!

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Customer reply replied 4 months ago
Thanks for your answer. For your knowledge, I added the pint of catalaclean according to the instructions
and did not notice any difference. Your answer supports my data where sensor 1 and sensor 2 are almost a mirror image, especially when the voltages that respond to the (fuel trim?) are almost the same waveform with a delay and nearly the same volts. I didn't notice a flat line, and watched the sensors warm up where they both started at 0 volts then at coolant temp of 140F then were pretty much hovered around .2 to .7 volts. I agree a cat converter is probably the issue but will take it to a dealer before I have the work done.

You are very welcome and usually the rear sensor won't flatline at a specific voltage, but the better the converter is cleaning the closer to 1. volts it will sit and longer.

Please let me know if there is anything else I can do to help and also kindly remember to rate my answer.

Thank you

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Customer reply replied 4 months ago
I may call you at a later time,
but am not able to now.
Is there any way a link can be emailed to me and the times that I can call to reach you?
Thanks

Sorry to say it's the site promoting the call and not myself. I am deaf and don't use the telephone. To many years in the shop without hearing protection. There are links to get you back here and I believe once you rate you can also "favorite" me so you have a direct link to ask other questions.

carguy1
carguy1, auto technician
Category: Toyota
Satisfied Customers: 27,749
Experience: 25 Years experience all makes and models.Nissan factory trained,Certified Subaru Tech
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Customer reply replied 4 months ago
Thanks ok, I will do the favorite button and do intend to contact you soon,
please send instructions for me to sign up for the fee also. This is a good service and I am happy to pay for it.

Thank you for the rating, I believe there should be a pop up to sign up for the subscription plan. If you have a blocker you might want to turn it off for the site and see. Otherwise contact customer service, like you I simply use the site.

Thanks again and have a great night!

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