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P0420 Error Code Plan Of Action Please


TANTO
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2001 RX300, 80k miles, getting P0420 "catylist efficiency below threshold". As i have a hard time believing i have a bad cat with this mileage, I'm thinking about replaceing the rearmost A?F sensor, and then perhaps the others also. Comments please? I noticed there are several sensor brands available. Any of these to stay away from. First post. TIA

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2001 RX300, 80k miles, getting P0420 "catylist efficiency below threshold". As i have a hard time believing i have a bad cat with this mileage, I'm thinking about replaceing the rearmost A?F sensor, and then perhaps the others also. Comments please? I noticed there are several sensor brands available. Any of these to stay away from. First post. TIA

Don't replace your A/F sensors. The problem is with your converter(s). Unfortunately, the early models didn't differentiate which of the three converters was at fault. You can try one at a time or just forget about it. Don't know about emission testing in your area. People usually get very discouraged when I tell them it may be any one of three very expensive parts.

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2001 RX300, 80k miles, getting P0420 "catylist efficiency below threshold". As i have a hard time believing i have a bad cat with this mileage, I'm thinking about replaceing the rearmost A?F sensor, and then perhaps the others also. Comments please? I noticed there are several sensor brands available. Any of these to stay away from. First post. TIA

Have you recently had a period, even brief, or TC or VSC activation..?

Those use EFI fuel starvation to dethrottle the engine leaving "pure oxygen" reaching the catalyst. Mine will clear those codes in 50-100 miles.

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