2002 Lexus GS300 3.0L PO430

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2002 Lexus GS300 3.0L PO430

Postby Bubeh » Mon Mar 19, 2018 5:48 am

2002 Lexus GS300 3.0L...this car showed PO430. Upon inspection, O2 (B2S2) was so badly fused to the cat that upon removal, that part of cat where sensor was plugged in broke. I suspect this was the cause of the fault code. Prior to removing the sensor, I scoped upstream and downstream O2 for B1 and B2 sensors (yellow trace is B2S2)...
IMG_20180318_232600.jpg


Owner replaced rear cat and its corresponding B2S2 with an after market. I did another scope to compare the before and after condition of all sensors (yellow trace is B2S2)...
IMG_20180318_090846.jpg


Will the bottom waveform warrant a fix on the PO430 code?
Bubeh
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Re: 2002 Lexus GS300 3.0L PO430

Postby victor2k » Mon Mar 19, 2018 7:18 am

Hello,
Based only on the attached image you have a low OSC but ...
Perform a diagnose with Techstream and look at the Catalyst Efficiency and you will find the answer:pass/fail .
You can have passive or active Air/Fuel ratio monitor,I think in 2002 -2003 the passive monitor was discontinued...if your catalyst monitoring system is active then you can't fool it(it plays with some small injections to see how the sensors and catalyst will respond).
active monitors zoomed.PNG

Prior to testing the exhaust sensors or catalyst run the engine in P between 2000-3000 rpm for aprox 3-5 minutes.
This will ensure that the exhaust sensors and the catalyst are at the operating temperature and ready for test.
1.Try to alternate the engine speed between 2000 and 3000 rpm at every 2 seconds and make a capture and in this first test you will check your oxigen sensors:fail or pass .
2.For the second test of oxigen or A/F sensors you will need to use Techstream and control the injection volume between +25% and -12.5% and here you can see the oxigen storage capacity of your catalyst(5 in the attached image)
OSC.PNG

3.the third test is to drive the vehicle with the engine at the operating temperature under heavy acceleration (fuel enrichment) and heavy deceleration(fuel cut) cycles capturing the sensor values(sometimes the after-market catalyst work well under the the low -medium load but not under the heavy load).
You can use for comparison the captured values from bank 1 as reference(at least you have only P0430 and not P0420),measure the good OSC from second test.
Regards
victor2k
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Re: 2002 Lexus GS300 3.0L PO430

Postby Bubeh » Mon Mar 19, 2018 3:44 pm

Thank you so much for your prompt reply...very much appreciated.

I do not have the Toyota Techstream software unfortunately. But I will do the other test you mentioned.
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Re: 2002 Lexus GS300 3.0L PO430

Postby Bubeh » Tue Mar 20, 2018 7:58 pm

so far i did all test, minus techstream, and catalyst monitor, O2 sensor monitor and O2 sensor heater monitor indicated a PASS...
Attachments
cat monitor.jpg
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Re: 2002 Lexus GS300 3.0L PO430

Postby Bubeh » Tue Mar 20, 2018 8:02 pm

IMG_20180320_132500.jpg
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