e30antonio Posted January 31, 2021 Share Posted January 31, 2021 I have a p0430 "Catalyst system efficiency below threshold, Bank 2" light on my 2000 LS400. Using the Torque Pro app, here is what I got for the O2 sensors on both banks with the engine at temperature and at idle. The green spikes are where I brought the revs up to about 1700 RPM. Both pre-cat sensors look like they're doing fine. The after-cat sensors seem to be constant but very low in voltage. At first, I had a p0171 System Too Lean, Bank 1. So I swapped sides with the pre-cat sensors. Then I got p0171 again. Then, I fixed some vacuum leaks and cleaned the MAF. Now, I'm stuck here on p0430. After driving around and turning the car on/off the Check Engine light has not lit up...so far. (I did not reset the light with the scanner). Your thoughts? Quote Link to comment Share on other sites More sharing options...
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