2001 camry I4 SEDAN P0420 error help

hi gyes, I just had an engine check light come on after almost 110000 miles. It was told to me by auto zone that this is P0420 error code. What does this mean? typically what?s the repair required for this? the guy at autozone also told me that I would need 2 o2 sensors, one before the CAT and one after. Can I buy aftermarket universal parts and not the OEMs as the 2 sensors would cost $ 440 together.

Please advise if anyone has unfortunately :( gone thru this. Thanks.

Reply to
cam
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P0420 is "catalyst system efficiency below threshold - bank 1", and 9 times out of 10 it means you need a new catalytic converter. But, to be sure you should find someone who can read the waveforms of your O2 sensors and perform an oxygen capture test on the converter to be sure. Don't let guys at a parts store tell you what's wrong with your car. They aren't technicians.

Reply to
qslim

The O2 sensors fail much more frequently that the converters themselves.

Reply to
Travis Jordan

Yeah, they do. But when they fail you don't usually get just a P0420 code by itself.

Reply to
qslim

"" wrote: > Yeah, they do. But when they fail you don't usually get just a > P0420 code > by itself.

Thanks folks, Basically what I need is a detailed diagnostic test rather than just a quick code retrieval. Is that what you guys would suggest? It was even my understanding that before CAT, the o2 sensors would fail. What?s the likelihood of both failing simultaneously? Thanks again for all your answers.

Reply to
cam

You'll need a way to observe o2 sensor voltages, be it with a scanner at the OBDII port or a good logging meter at the ECM terminals. The front sensor, after the car is warm and engine racing at around 2500 - 3000 rpm, should cycle from .2v to .8v roughly every 8 - 10 seconds. The rear sensor should be a nearly flat line, with a cycling frequency no less than around

30 seconds or so. This is a normally operating system. If the rear sensor matches the front sensor waveform, you have a cat that is not doing its job. If the front sensor matches the rear sensor waveform, you have a sensor issue. But, if the latter is the case you would (at least in the case of most Toyotas) most likely have an additional trouble code indicating a range/performance problem with the front 02 sensor. Thats why a 420 code alone usually indicates a converter problem. Barring all this you can also perform an oxygen capture test to measure the residual unused oxygen coming from the converter, but this requires a gas analyzer. An infrared thermometer can also be used to check for uneven temperatures across the bottom of the converter, indicating a problem. Also, there is no rule indicating which component will fail first. There is no justification in replacing an oxygen sensor (or two) just because converters usually last longer. Any real technician with half decent equipment should be able to figure this out in less than ten minutes.
Reply to
qslim

after the car is warm and engine racing at around 2500 - 3000 rpm, should cycle from .2v to .8v roughly every 8 - 10 seconds ~~~~~~~~ qslim - thanks for contributing your experience to the group.

------ but doesn't that first 02 sensor cycle much more frequently than once in 8 seconds?

Reply to
Daniel

Yeah Daniel, I misspoke (sorry). I meant to write that the front sensor should cycle about 10 times every 8 to 10 seconds. Good catch.

Reply to
qslim

"" wrote: > Yeah Daniel, I misspoke (sorry). I meant to write that the > front sensor > should cycle about 10 times every 8 to 10 seconds. Good catch.

folks, thanks for all the words of experience. Currently, although the car is running with a normal mileage, I have been unable to get it diagnozed and have been driving it at least 20 miles a day. Would any one know the after-effects or deterioration of this condition not fixed in due time. (I have been unable to get the error P0420 fixed so far)

Thanks once again, CAM

Reply to
cam

"cam" wrote: > folks, > thanks for all the words of experience. > Currently, although the car is running with a normal mileage, > I have been unable to get it diagnozed and have been driving > it at least 20 miles a day. > Would any one know the after-effects or deterioration of this > condition not fixed in due time. (I have been unable to get > the error P0420 fixed so far) > > Thanks once again, > CAM

Sounds like your convertor is already gone. Can?t hurt to drive it. I agree with Suckers, you need a convertor, the downstream O2 is doing its job, it hasn?t failed.

Reply to
Fourmiler

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