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Discussion Starter · #1 · (Edited)
*Just wanna apologize in the begginning for any confusing parts in my writing, im not the best with terms, lol.*

So my 2001 Lexus Is300 has an srt intake and mazzuri headers. I got my o2 sim on thinking everything would be good, but about a month into having both installed my CEL popped up. Figured, ok might not effect anything, lots of cars have em on. Then a day later my trac control light starts flashing, then i start to wonder what it could be. So i search and search around the site for help on what could fix the problem. Meanwhile, my car is starting to go into limp mode while driving, (slowly revving to 3k while trying to cruise, then jumps on the gun after 3k while trying to cruise.) I wasted a ton of gas because of this. I take my car to Autozone and have them read the codes, the dude that helped seemed kinda pissed i had so many, cause he had to print me out 11 different code slips, lol. Main codes were P0141, P0155, P0161. Some for cylinders 1,2,3 not working and some other ones i cant remember. So im reading and people are saying, replace o2 sensors, recheck wiring, getting a new o2 sim and what not. I figure i'd try those things, but most of them are also saying the CEL comes back, so i figure i might as well wait till i try and it hopefully goes away for awhile. So while im searching on for solutions, I say whats up to longnights on AIM. Longnights and I are thinking of what could be the problem, he explains to me the plugins for which o2 sensors are in the engine bay, what could cause the misfiring and cel. We then figure out that the o2 sensor i left in my stock headers would be one that i actually needed, but not plugged in. So i go out to my garage, wd-40 the shit outta that sensor and get it to come off. Then i plug that into one of the sensor plugins up towards the front of the engine. I also tapped a few wires in my ecu because one of the sensors i did have plugged in still were throwing a code off, meaning i had to tap that wire into a working o2 sensor. I reset my ecu and headed off to work, after work i noticed the CEL hadnt came on yet, i was pretty glad, i cruised around for a bit, and after a weekend, ive gone 100miles, CEL free. Cost me nothing but about 10min of time, which was time well spent, lol. Below will explain what i did:
1. Remove negative terminal from battery
2. Made sure i had 3 o2 sensors, not including the one under the car.
3. Plugged in my o2 sensors according to the picture on
O2 Sensor Diagram
My problem before doing this was i was missing an o2 sensor that wasnt plugged in. Meaning the wire i tapped into from sophie sleeps diagrams was tapping into a o2 wire with no o2 connected. After having connected all the o2 sensors plugged in the right spot and screwed into the right holes on the headers, be sure to tuck the front o2 sensor (red/orange tip) in a safe spot.
After doing that, i remembered that my o2 sensor i had plugged in the back of the engine wasnt working for some reason. So i got into the ecu while reading another one of Sophiesleeps diagrams, and tapped my b2s2 heater wire into my b1s2 heater wire on the left side of the ecu. Then i did the same to the other heater wires on the right side, b2s1 to b1s1.
Link to SophieSleeps Diagrams
4. Tape wires together, put cover back on ecu
5. Put negative terminal back on to battery
6. Turn car on and enjoy! :bigSmile:

I wanna thank Longnights for explanation on pretty much each sensor and helping me through the whole process, i also wanna thank sophiesleeps for the excellent wiring diagrams she had.
Sorry my story is kinda long, just felt i needed to share my story, perhaps help another member out in the future.
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