New O2 sensor (Bank 2, Sensor 1) flatlined

[aaronknotty]

So, I'm been having cold start up issues with my car. First it would misfire most days on cold startup, then when its warm, you turn it off then back on and it's fine. Been trying to fix the issue. Finally started looking around the O2 sensors cause I honestly don't know if they have ever been changed and its at about 200,000 miles. "2001 BMW 525i Wagon"

To get a better picture of what is going on I cleaned up around the upstream O2 sensors cause there was some oil. Wanted to make sure there wasn't a leak in the valve gasket, so i cleaned it up to see if it would leak later. Well... since doing that my car ran fine. Then one day the mpg gauge showed 8mpg! and i was feeling a loss of power. Thought it was weird, so I shut the car down, re-satarted later and it was fine. Well now its stuck in the bad little habit. Plus theres now a Catalytic converter bellow threshold code that popped up. I doubts its the Cat, cause i would't have been able to just re-set the issue like i did earlier if it was.

Like I said I narrowed it down to the O2 sensor area so i popped 2 new OEM Bosch sensors. And... no change. So I pulled out my very limited OBD Fusion scanner and pulled up the O2 sensors on the graph while running the car. Everything looks good except the Bank 2, Sensor 1 start up and then flatlines at the bottom of the graph. A.K.A my engine can't mix.

So!! the question that I have.

1. I guessing theres the possibility theres a short in the sensor wiring. But the fact that it started up then flatlined makes me think it may not? Or could that just be clunky OBD Fusion?

2. Are there fuses for the O2 sensor heaters? Is it possible i shorted a heater out during cleaning? Just used some brake cleaner on the outside of the connectors and under valve cover lip area. But all wiring is sealed so I feel like that could be ruled out.

3. Could a massive vacuum leak on the front affect this? I feel a large leak would affect both though...

4. Is there anything else I'm missing and should check?


I have CSV file from a short test i ran on the car. You can obviously see that there is something wrong with O2 sensor Bank 2, Sensor 1. it gives off so little its literally off the chart except in the middle. But even that is low. And massively throwing off the fuel trim. For some reason I can't add attachments. So here's the data. Thanks!





Time, Engine coolant temperature (F), Intake manifold absolute pressure (psi), Engine RPM (RPM), Intake air temperature (F), Mass air flow rate (g/s), Absolute throttle position (%), Commanded secondary air status, Location of oxygen sensors, O2 voltage (Bank 1 Sensor 1) (V), Short term fuel trim (Bank 1 Sensor 1) (%), O2 voltage (Bank 1 Sensor 2) (V), Short term fuel trim (Bank 1 Sensor 2) (%), O2 voltage (Bank 2 Sensor 1) (V), Short term fuel trim (Bank 2 Sensor 1) (%), O2 voltage (Bank 2 Sensor 2) (V), Short term fuel trim (Bank 2 Sensor 2) (%), Input voltage read by the scan tool (V)
11/23/2018 02:04:14.3302 PM,199.4,0,0,96.8,0,5.882353,4,51,0.235,0,0.33,99. 21875,0,0,0.48,99.21875,0
11/23/2018 02:04:19.3081 PM,199.4,0,0,96.8,0,5.882353,4,51,0.245,0,0.34,99. 21875,0,0,0.475,99.21875,11.1
11/23/2018 02:04:22.7110 PM,199.4,0,0,96.8,0,5.882353,4,51,0.255,0,0.345,99 .21875,0,0,0.47,99.21875,11.1
11/23/2018 02:04:26.1308 PM,199.4,0,0,96.8,0,5.882353,4,51,0.265,0,0.355,99 .21875,0,0,0.465,99.21875,11.1
11/23/2018 02:04:31.2096 PM,199.4,0,0,96.8,0,5.882353,4,51,0.275,0,0.36,99. 21875,0,0,0.465,99.21875,11.1
11/23/2018 02:04:36.7866 PM,199.4,0,0,96.8,0,5.882353,4,51,0.285,0,0.37,99. 21875,0,0,0.46,99.21875,11.1
11/23/2018 02:04:40.8441 PM,199.4,0,0,96.8,0,5.882353,4,51,0.295,0,0.375,99 .21875,0,0,0.455,99.21875,11.1
11/23/2018 02:04:44.6793 PM,199.4,0,0,96.8,0,5.882353,4,51,0.3,0,0.375,99.2 1875,0,0,0.455,99.21875,11.1
11/23/2018 02:04:54.5990 PM,194,0,0,96.8,0,5.882353,4,51,0.31,0,0.38,99.218 75,0,0,0.455,99.21875,11.1
11/23/2018 02:05:05.7569 PM,194,0,632,96.8,7,0,4,51,0.87,0,0.755,99.21875,0 ,0,0.605,99.21875,11.3
11/23/2018 02:05:16.2536 PM,194,0,1610,96.8,16.8,0,4,51,0.085,0,0.865,99.21 875,0,0,0.86,99.21875,11.3
11/23/2018 02:05:27.1401 PM,194,0,981,96.8,5.32,0,4,51,0.35,-3.125,0.82,99.21875,0.04,27.34375,0.945,99.21875,1 3
11/23/2018 02:05:34.3493 PM,194,0,1569,98.6,17.71,0,4,51,0.065,-6.25,0.27,99.21875,0.04,27.34375,0.955,99.21875,13
11/23/2018 02:05:52.1215 PM,194,0,827,98.6,17.71,0,4,51,0.345,-3.125,0.14,99.21875,0.035,27.34375,0.95,99.21875,1 3
11/23/2018 02:05:55.6153 PM,194,0,731,98.6,5.25,0,4,51,0.195,2.34375,0.19,9 9.21875,0.035,27.34375,0.95,99.21875,13
11/23/2018 02:06:04.5008 PM,194,0,727,98.6,5.04,0,4,51,0.78,0.78125,0.315,9 9.21875,0.03,27.34375,0.95,99.21875,12.5
11/23/2018 02:06:17.6742 PM,194,0,715,100.4,4.97,0,4,51,0.05,-4.6875,0.795,99.21875,0.025,27.34375,0.94,99.21875 ,12.5
11/23/2018 02:06:22.1041 PM,194,0,721,100.4,5.04,0,4,51,0.785,0.78125,0.74, 99.21875,0.02,27.34375,0.94,99.21875,12.9
11/23/2018 02:06:25.5044 PM,194,0,1019,100.4,11.69,1.568627,4,51,0.87,-7.8125,0.845,99.21875,0.02,24.21875,0.94,99.21875, 12.9
11/23/2018 02:06:32.1765 PM,194,0,1019,100.4,28.14,22.7451,4,51,0.26,-4.6875,0.75,99.21875,0.005,14.84375,0.93,99.21875, 12.9
11/23/2018 02:06:51.2719 PM,194,0,1697,84.2,37.24,1.960784,4,51,0.195,1.562 5,0.825,99.21875,0,0,0.76,99.21875,12.9
11/23/2018 02:06:54.6780 PM,194,0,1035,84.2,4.9,0,4,51,0.08,3.90625,0.73,99 .21875,0,0,0.81,99.21875,12.9
11/23/2018 02:07:05.1512 PM,194,0,955,84.2,4.69,0,4,51,0.88,-1.5625,0.395,99.21875,0,0,0.865,99.21875,12.9
11/23/2018 02:07:37.1077 PM,194,0,1470,84.2,26.18,18.82353,4,51,0.785,-1.5625,0.825,99.21875,0,0,0.885,99.21875,13
11/23/2018 02:07:43.9513 PM,194,0,1340,89.6,19.04,7.843137,4,51,0.08,-3.90625,0.13,99.21875,0,0,0.795,99.21875,13
11/23/2018 02:07:51.7631 PM,194,0,1247,89.6,4.76,0,4,51,0.615,0.78125,0.69, 99.21875,0,0,0.775,99.21875,13
11/23/2018 02:08:15.4909 PM,194,0,1313,89.6,4.62,0,4,51,0.08,2.34375,0.77,9 9.21875,0,0,0.81,99.21875,13
11/23/2018 02:08:22.6311 PM,194,0,1167,89.6,4.62,0,4,51,0.775,0,0.665,99.21 875,0,0,0.81,99.21875,13
11/23/2018 02:08:35.9179 PM,203,0,1002,93.2,4.41,0,4,51,0.825,3.90625,0.625 ,99.21875,0,0,0.785,99.21875,13
11/23/2018 02:08:48.3626 PM,204.8,0,724,93.2,4.97,0,4,51,0.13,1.5625,0.775, 99.21875,0,0,0.775,99.21875,12.7
11/23/2018 02:08:55.2227 PM,204.8,0,724,93.2,4.83,0,4,51,0.655,1.5625,0.78, 99.21875,0,0,0.77,99.21875,12.9
11/23/2018 02:09:06.0664 PM,204.8,0,721,93.2,4.83,0,4,51,0.13,0.78125,0.775 ,99.21875,0,0,0.77,99.21875,12.9
11/23/2018 02:09:17.9870 PM,204.8,0,720,93.2,4.76,0,4,51,0.225,2.34375,0.77 5,99.21875,0,0,0.765,99.21875,12.6
11/23/2018 02:09:21.6039 PM,204.8,0,723,96.8,4.83,0,4,51,0.62,1.5625,0.78,9 9.21875,0,0,0.765,99.21875,12.6
11/23/2018 02:09:24.9389 PM,204.8,0,714,96.8,4.83,0,4,51,0.1,0.78125,0.775, 99.21875,0,0,0.765,99.21875,13
11/23/2018 02:09:28.6064 PM,204.8,0,714,96.8,4.9,0,4,51,0.55,0.78125,0.785, 99.21875,0,0,0.765,99.21875,13
11/23/2018 02:09:35.7337 PM,204.8,0,714,96.8,4.83,0,4,51,0.095,1.5625,0.775 ,99.21875,0,0,0.765,99.21875,13
11/23/2018 02:09:44.1664 PM,204.8,0,720,96.8,4.83,0,4,51,0.1,1.5625,0.77,99 .21875,0,0,0.845,99.21875,13
11/23/2018 02:09:51.3395 PM,204.8,0,1607,96.8,17.08,7.058824,4,51,0.095,-1.5625,0.3,99.21875,0,0,0.845,99.21875,12.8

[geargrinder]

WRONG PLACE. Not really a "Touring" question. Should be in the main forum. Get a mod to move it. That's why nobody replying.

[JimLev]

Guess he wasn't to interested in an answer. I just happened to see his post own my own.
Only replying to get it to the top of the page, maybe he'll get an answer.