8:00 AM Two days ago i sprayed with contact cleaner the front of the two connectors for both oxygen sensors. For that i went in the parking lot at the street (left in this picture). WD40 Contact Cleaner dries very fast but i waited more than ten minutes before i plugged them.

But i sprayed them from front and all around neglecting the back where some of the dissolved stuff gathered possibly shorting the terminals after the cleaner dried.

Today i am waiting for a new sensor from Amazon. So this morning after hours of thought i went outside to correct that, suspecting that dirt was shorting the signal terminal to the ground one (and would make replacing of the sensor which is indeed shut also probably being shorted senseless and useless) but that stuff was stubborn, temperature outside is 45 degrees so i had to come back inside, search for a brush to help the solvent.

Nobody was outside at this hour and solvent smell did not come through the open door inside. When i was about done including about 5 minutes of drying and shut the hood two small people, pretendedly Mexican passed and he shook his head, vigorously a number of times, like saying "NO" in my direction though i did not say anything to them.

9:10 Now i read 0.45 volts at the connector and 1.275 on the scanner and i can't find a ground at sensor connector. Is my PCM fried?

10;20 The black BMW has thundered and i feel stingy dust in my eyes and throat.

10:25 Ok i finally understood how these things work. Most of the stuff i read before was about old style or narrow band sensors.

But after i plugged the sensor one more time and now i may have just fried it. I don't got anymore .45 volts at any of the pins. I get 12 volts on pin 5, 2.5 volts at 2 (or the other way around), and also can't find ground. Sensor is out for delivery.

10:50 I am wasting my time. Need to wait for the sensor and plug it in. But yes cleaning the connector 3 times now could not have been bad since dirt can cause false readings. Thinking. For one of the most important if not the most important sensor in you vehicle regarding mileage and protecting the engine i would have expected a more solid connection.

They way it is right now, if it gathers dust and when water droplets get on it it during rain or simply high humidity and salt at the ocean, it will slightly short the pins, causing false readings and variation in mileage.

As for as cleaning. I would recommend brushing the dust among to terminals in the back of it. Using contact cleaner could make a mess and you could get in trouble like i just did.
11:33 Ok why is it happening only to me? I am getting conflicting info about the upstream sensor in my car. While the scanner reports the B1S1 (Bank one sensor one) in volts and the B1S2 in mA, google answers say the upstream sensor is a wideband one and should give the results in mA.

Ok so the 1.275 volts steady i am now getting on the scanner is not too high. But before this whole episode i was getting 0.8 volts.

On the other hand on the scanner i get mA on the second sensor. So are they both wideband?

11:55

2:10 PM 1.275 volts is normal when you unplug the sensor and plug it back in with the ignition on. The reason that sensor was not working (also getting no ground at the connector) was it was loose. When i put that tool on it today it came out by hand. Don't know what else to say.

They usually are becoming more and more stuck, not loose with time (i was preparing for a fight when taking out).

Ok an idea came to me. Should check the second one as well. Going for a trip to Lincoln City just to see how it works, mileage and stuff.

2:42 I did a short drive and i can say it drives dramatically better. I never knew  how this car should drive until now (much more power and gas pedal response).

2:48 I was regularly vacuuming the intake of the other Elantra with a modified mat pump. With the latest version of the catch can i now am getting almost no oil in there but lately it had symptoms and today i looked with a mirror projecting light from sun and saw small puddles of oil in the intricacies of that composite thing.

I was planning for some time and talked in the car about it and today when i tried to do it the pump literally fell apart in my hands (the plug). I tried to fix it but then the spring between fuse and the tip vaporized. So i put all the pieces together to make sure i got them and they did not end in the intake LOL.

Other thing that i discovered when i tried to pull oil out of intake was the air filter gasket got pinched and was allowing more air to pass, which translate in more lean mixture, loss of power, the same as with the loose sensor and that is critical on the freeway whey then are coming with the big tanks from behind. BTW i have to check the lug nuts, i feel they are loose again and that also cause loss of power.