Japasie Posted October 13, 2021 Report Share Posted October 13, 2021 Hello, I am new to the forums and am having trouble diagnosing these two codes. I first took it to Autozone and had them read it which recommended I replace the MAP sensor which I have, but after deleting the codes and driving again they have returned. I have purchased an Innova 3040 RS. On the initial snapshot it shows STFT B1 0% LTFT B1 0%. STFT B2 -3.9% LTFT B2 0.8%. On live Data it shows O2S B1S1 0.0-0.800V STFT B1 S1 0-5.5%. O2S B1 S2 0.0-0.800V STFT B1 S2 99.2%. O2S B2 S1 0.0-0.800V STFT B2 S1 0-5% O2S B2S2 0.0-0.800V STFT B2 S2 99.2%. Do these readouts indicate an exhaust leak or faulty O2 sensor? Any help would be appreciated. Quote Link to comment Share on other sites More sharing options...
5rebel9 Posted October 13, 2021 Report Share Posted October 13, 2021 Welcome to the Forum. How many miles on this DJ? IF over 100k miles I'd suggest start with exhaust system check for leaks between the up stream and downstream O2 sensors. Then most commonly would be UPSTREAM O2 sensors. They are the main use sensor for fuel system trim control AND are recommended to be replaced every 100K miles. Your codes indicate that it is running too rich on both banks. Not knowing just how it is running or maint history, there are a number of things that can make an engine run "rich" from worn plugs to intake leaks to bad fuel injectors. Good luck and I hope this helps. Quote Link to comment Share on other sites More sharing options...
Japasie Posted October 13, 2021 Author Report Share Posted October 13, 2021 Thanks for the reply. By Upstream sensor, I'm assuming you are talking about sensor 1 on both banks? Quote Link to comment Share on other sites More sharing options...
John/Horace Posted October 13, 2021 Report Share Posted October 13, 2021 Quote Link to comment Share on other sites More sharing options...
5rebel9 Posted October 13, 2021 Report Share Posted October 13, 2021 35 minutes ago, Japasie said: Thanks for the reply. By Upstream sensor, I'm assuming you are talking about sensor 1 on both banks? YES the B1S1 and B2S1, they are the "upstream"(in the exhaust manifolds). The "downstream" B1S2 and B2S2 are in the converters. Cracks in exhaust or in the exhaust manifolds can set these codes along with other items I posted. Quote Link to comment Share on other sites More sharing options...
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