2009 GX470 O2 sensor/catalytic converter question (1 Viewer)

CloudCity

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I am helping out my bud who bought a 2009 GX recently since I have a 100-series LX and like to poke around these rigs. He had the classic Traction/Engine lights pop up and I ran the codes. Showed "P0420 Catalyst System Efficiency Below Threshhold." I cleared the code and we too it for a drive of about 40-mins and the lights didn't reappear yet. I did note that my OBDii showed a reading for Sensor 2 of 80, but that Sensor 1 showed 0.00 readout.

My questions are does this indicate an O2 sensor failure, and if so, how do I determine which on on that bank 1?
Also, might this indicate a catalytic converter issue, or is it most likely an O2 sensor?

Thanks much!
 

saucebox

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Happens to my LX on long trips. I just clear it and wait until the next long trip when I need to clear it again. Sometimes it's a few months in between, sometimes weeks. Zero change in mileage or any other measurable metric as best I can tell (and I track every single gallon).

Long term I need to find the root of it as well. But in the short term, it's likely of little concern.
 

Vlad

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Code should say bank and sensor. I get them after I drive city and get on the highway (especially with altitude change). I just clear them. If they come back persistently, swap the sensor with a denso unit. Do not use Bosch.
 
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Did you do a write up on it? Trying to determine if this is in my ability to do...
I did not do a write up.
For the upstream sensors, they seem to be designed for a service tech with tiny hands and long skinny arms.

It was a challenge for me and I consider myself very mechanically inclined.
 

CloudCity

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I wanted to come back to finalize this thread since I forgot to, but the GX ended up needing one Cat replaced. The code came back after a few weeks. That was what finally resolved the code reappearing.
 
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I wanted to come back to finalize this thread since I forgot to, but the GX ended up needing one Cat replaced. The code came back after a few weeks. That was what finally resolved the code reappearing.

mid you don’t mind me asking, how much did the cat end up costing you?
 

CloudCity

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mid you don’t mind me asking, how much did the cat end up costing you?
The GX belongs to a friend but we just checked his paperwork from when he had the repair done at the local Lexus dealer and it was $945 for the part and a grand total of $1,567.56 for the full repair including diagnostics, labor, and associated gaskets, etc. Mind you these are all Lexus dealer prices. Our local (Kuni Lexus of Beaverton/Portland) is a top notch operation tho and I use them for some things too.
 
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Thanks for the update. I'm getting both P0420 and P0430 appearing constantly for the last few months. Clearing the codes only lasts 20 to 40 miles.

My code reader only tells me that it's bank 1 for P0420 and bank 2 for P0430, but not which sensor.

Since I replaced the pair of downstream sensors 4 years ago, I'm going to replace the pair of original (18 year old) upstream sensors this time around with Denso ones from RockAuto.

Best case scenario, the upstream sensors fix my issue so I can pass the smog test coming up in a month or two.

Worse case scenario I need to replace the upstream cats at God-knows what price. Parts seem to range from $450 to $650 each depending on web site and if toyota or lexus brand. So, I figure pray and hope the cheap parts fix the issue.

Anyone know if these are the right part numbers?

17105-50170, Cat Converter with Integrated Manifold (Left = Drivers side in USA)
17104-50180, Cat Converter with Integrated Manifold (Right = Passenger side in USA)

Parts seem to be cheaper if I buy for Toyota 4Runner 8-cyl than Lexus GX470, but only like $40 cheaper each.

2376C96A-4BCF-462E-8410-FBF191D8C009.jpeg
 
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CloudCity

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Hmmmm, my buddy's invoice shows 17150-50050 as the "left side catalyst" manifold assembly.
Also:
17198-50010 for manifold gasket
90080-43036 for exhaust pipe gasket
90080-17187 nut, lock (x8 pieces)
 
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Thanks for posting the part numbers for the 2009 gx470. I have a 2003 and it looks like 2003-2004 use a different part number for the integrated cats than the 2006-2009
 

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