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Discussion Starter #1
Hi.

We've got a 2011 RAV4 2.5L that's had the p0420 code for about two months now. The code came up after we replaced both sensors, downstream first then the upstream afterwards. We havent really driven the car that much, probably about 1k miles total in both months. But during the times we did drive it, all we have noticed is a MPG drop in our drives (because of running rich I'm assuming?).

That leads me to my question. How likely is it that it's actually the O2 sensor(s) that's still the problem for this code? We replaced the downstream sensor when the P0136 code came up. After about fifty miles, the same code came up again and then afterwards, we replaced the upstream sensor. After another fifty miles, the p0420 came up and no longer the P0136 code.

Furthermore, if it's likely that the CAT needs to be changed, will I be wrong with going OEM or is there another cheaper yet OEM quality aftermarket solution (i.e DENSO)?

Furthermore, I'd like to ask about some of the preventative maintenance we should start looking into. We've had the car since new, and it has about 126k miles on it now. We've replaced the spark plugs at about 120k miles, did rotors and pads just last month, front and back wheel bearings last month as well (thank you east coast shitty roads), as well as a full coolant flush about six months ago.

We're looking into doing a transmission fluid change as well. Any other thing that we should also do (that we can do in our garage)?
 

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The OEM catylitic conveter are expensive but last much longer then aftermarket ones. Some people replace the cat and still get the code so they use O2 spacers.

Did you clear the P0420 code after you installed the second O2 sensor? I heard some people clear the code and they don't come back.
 

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Discussion Starter #5
The OEM catylitic conveter are expensive but last much longer then aftermarket ones. Some people replace the cat and still get the code so they use O2 spacers.

Did you clear the P0420 code after you installed the second O2 sensor? I heard some people clear the code and they don't come back.
I've cleared it about 4 times since the code has come up. Each time after, it comes back on quicker.

OEM Cat is about 600 with the manifold. Is there any aftermarket solution that has similar quality but is on the less expensive side?

Thanks for your response and time.
 

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I've cleared it about 4 times since the code has come up. Each time after, it comes back on quicker.

OEM Cat is about 600 with the manifold. Is there any aftermarket solution that has similar quality but is on the less expensive side?

Thanks for your response and time.
I have not heard of any aftermarket cat that last very long. But you can check out Rockauto and select one from there. Since you don't put very much mileage every year one of these aftermarket cat might work for you.
 

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Discussion Starter #7
I have not heard of any aftermarket cat that last very long. But you can check out Rockauto and select one from there. Since you don't put very much mileage every year one of these aftermarket cat might work for you.
Might as well do that.

I'd like to ask, regarding the O2 Sensors, is there any way to test them and check if they're working correctly besides reading them from an OBD2 reader?
 

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Techstream Windows 10 install instructions

 

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Hi.

We've got a 2011 RAV4 2.5L that's had the p0420 code for about two months now. The code came up after we replaced both sensors, downstream first then the upstream afterwards. We havent really driven the car that much, probably about 1k miles total in both months. But during the times we did drive it, all we have noticed is a MPG drop in our drives (because of running rich I'm assuming?).

That leads me to my question. How likely is it that it's actually the O2 sensor(s) that's still the problem for this code? We replaced the downstream sensor when the P0136 code came up. After about fifty miles, the same code came up again and then afterwards, we replaced the upstream sensor. After another fifty miles, the p0420 came up and no longer the P0136 code.

Furthermore, if it's likely that the CAT needs to be changed, will I be wrong with going OEM or is there another cheaper yet OEM quality aftermarket solution (i.e DENSO)?

Furthermore, I'd like to ask about some of the preventative maintenance we should start looking into. We've had the car since new, and it has about 126k miles on it now. We've replaced the spark plugs at about 120k miles, did rotors and pads just last month, front and back wheel bearings last month as well (thank you east coast shitty roads), as well as a full coolant flush about six months ago.

We're looking into doing a transmission fluid change as well. Any other thing that we should also do (that we can do in our garage)?
To clear code p0420 permanently you need O2 sensor adopter from Amazon or AliExpress shop to fix this code and increase fuel economy of your vehicle. I had saw problem some months ago after notice my downstream O2 sensor had cracks beneath the tread and this what I did to solve


Sent from my iPhone using Tapatalk
 

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To clear code p0420 permanently you need O2 sensor adopter from Amazon or AliExpress shop to fix this code and increase fuel economy of your vehicle. I had saw problem some months ago after notice my downstream O2 sensor had cracks beneath the tread and this what I did to solve


Sent from my iPhone using Tapatalk
I already suggested that O2 Spacer and the OP is planning to buy the Cat instead. He may even get the code after the cat is installed like some members.
 

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We used to use a spark plug extender on the downstream 02 sensor to 'fool' the 02 sensor into thinking the cat was good. I don't know if that still works and you only get by in 'non-emission' testing areas because a good inspector with a mirror can spot this. I only recommend trying this for a test. lol
 

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How likely is it that it's actually the O2 sensor(s) that's still the problem for this code? We replaced the downstream sensor when the P0136 code came up. After about fifty miles, the same code came up again and then afterwards, we replaced the upstream sensor. After another fifty miles, the p0420 came up and no longer the P0136 code.
For what it's worth, many years ago the check engine light came on for our 4Runner, and our mechanic said it was an O2 sensor and he replaced one of them. But the check engine light was still on a while later (I recall they only reset after so many starts of the vehicle), so he replaced the other O2 sensor. The check engine light still (!) stayed on, and a member of the 4Runner forums suggested replacing BOTH O2 sensors at the same time, which we did. The check engine light hasn't been on since. So, we were thinking that if one O2 sensor is faulty then it'll destroy the other one, and they both have to be replaced at the same time. Not sure if this helps, but maybe one of the more knowledgable folks here can determine if this makes sense?
 

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Hi.

We've got a 2011 RAV4 2.5L that's had the p0420 code for about two months now. The code came up after we replaced both sensors, downstream first then the upstream afterwards. We havent really driven the car that much, probably about 1k miles total in both months. But during the times we did drive it, all we have noticed is a MPG drop in our drives (because of running rich I'm assuming?).

That leads me to my question. How likely is it that it's actually the O2 sensor(s) that's still the problem for this code? We replaced the downstream sensor when the P0136 code came up. After about fifty miles, the same code came up again and then afterwards, we replaced the upstream sensor. After another fifty miles, the p0420 came up and no longer the P0136 code.

Furthermore, if it's likely that the CAT needs to be changed, will I be wrong with going OEM or is there another cheaper yet OEM quality aftermarket solution (i.e DENSO)?

Furthermore, I'd like to ask about some of the preventative maintenance we should start looking into. We've had the car since new, and it has about 126k miles on it now. We've replaced the spark plugs at about 120k miles, did rotors and pads just last month, front and back wheel bearings last month as well (thank you east coast shitty roads), as well as a full coolant flush about six months ago.

We're looking into doing a transmission fluid change as well. Any other thing that we should also do (that we can do in our garage)?
I have 05 RAV4 the CAT died with about 300,000 I try to avoid using 87 octane gas. I use 89 or 93 most of the time. I replaced the original CAT with 5 year warranty CAT and have had to use the warranty twice. The converter keeps dying. The vehicle now has 445,000 miles on it. It's gonna be one of those parts that fails every few years so buy a converter with a long warranty.
 

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Discussion Starter #18
For what it's worth, many years ago the check engine light came on for our 4Runner, and our mechanic said it was an O2 sensor and he replaced one of them. But the check engine light was still on a while later (I recall they only reset after so many starts of the vehicle), so he replaced the other O2 sensor. The check engine light still (!) stayed on, and a member of the 4Runner forums suggested replacing BOTH O2 sensors at the same time, which we did. The check engine light hasn't been on since. So, we were thinking that if one O2 sensor is faulty then it'll destroy the other one, and they both have to be replaced at the same time. Not sure if this helps, but maybe one of the more knowledgable folks here can determine if this makes sense?
Hi, thanks for the reply.

Maybe it might be specific to the vehicle? Not sure though.
 

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Discussion Starter #19
I have 05 RAV4 the CAT died with about 300,000 I try to avoid using 87 octane gas. I use 89 or 93 most of the time. I replaced the original CAT with 5 year warranty CAT and have had to use the warranty twice. The converter keeps dying. The vehicle now has 445,000 miles on it. It's gonna be one of those parts that fails every few years so buy a converter with a long warranty.
Yeah, at this point, if I choose to replace the cat, I might just go OEM for the warranty.

Just waiting for my techstream to come in so I can get some further diagnosis.
 
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