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o2 Sensor Stuck at 5v

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FunkDocta

10+ Year Contributor
40
2
Feb 20, 2009
Orlando, Florida
So I just recently got ecmlink and everything was going smooth until I noticed my o2 voltage was stuck at 5v. It should not even reach that high so what is going on. I keep getting these two codes p0304 and p0125 that cause me to run like crap. My car's AFR shoots up to 18+ and starts bucking like a horse. At first I thought misfire but I changed the spark plugs with brand new NGK brp7es gapped to 0.28 still misfire from cylinder #4. I bought a new NGK wireset and still misfires and I get the same p0304 code. I have not tried testing the coil pack of yet but will soon.




At this point I am getting frustrated so I decide to buy a new o2 sensor and see if that fixes my o2 voltage problem.........WRONG!!!!!!! Brand new Bosch oem style o2 sensor and still stuck at 5v. I am really worried that this will damage my ecu which is brand new (purchased from dsmchips.com). I tried unplugging the sensor and see if the voltage drops but still even with the o2 sensor disconnected my logs read 5v no drops.




I tried locking the car in open loop mode and it helped a bit for a while but eventually the two same codes came back (p0125 & p0304) and the car feels like it is missing. I am thinking this has to be a wiring problem some where in the harness but praying it is something simple I over looked.




I have three logs the first is with the o2 sensor unplugged, the second it is plugged back in, and finally the third the car is locked in open loop mode. Any help is appreciated at this point in time I just want my car running smooth for once.
 

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