Quote:
Originally Posted by performanceisland  my o2 sensor plug has a black wire, grey wire and two white wires, then at the plug they turn into the following:
black goes to yellow
grey goes to black
white goes to green
white goes to brown
on a 1999 318TI
i read the following on pelican article:
Lastly, with a 4-wire oxygen sensor, the output signal works in a constant loop, essentially, the fuel injection computer sends a signal to the sensor, and the sensor then sends the signal back to the computer. This is achieved by having one wire carry the signal to the sensor, and then another wire carries the signal back to the fuel injection computer. You also have a wire carrying 12 volts to the heating element, and the last wire is the ground for the heating element. (pic o2_sensor_diagram_4 jpg) With a 4-wire sensor, you will need to measure the voltage fluctuations between the two signal wires. To do this, start the car and let it warm up. Next, disconnect the oxygen sensor and measure the voltage between the wires. Now take off the oil filler cap to simulate a rich running condition. Watch the voltage, if it begins to fluctuate rapidly, then the sensor is good and you’re done. If it stays the same, it’s probably fried. |
The two whites are heater wires the black is ground and the grey is signal. The O2 sensor is a voltage generator. It gererates voltage by the amount of oxygen in the exhaust. At least that is how I undersand them to work and how my simulator works.
If not how could the voltage fluctuate or be present at all if it is disconnected from the harness? Also running a O2 sensor in the exhaust stream without the heater wiries connected is a great way to burn it out real fast, just an FYI.
After speaking with you on the phone I think you have a wire mis-labeled.
O2 sensor wires to tap into O2 White = Heater
White = Heater
Grey = Signal
Black = Ground
After plug O2 wiring to DME cross-over wiring to tap into DME wiring: Black = Ground pin 46 DME
Yellow = Signal pin 19 DME
Brown = O2 Heater Ground pin 30 DME
Green = Connects to all red/white wiring 12 volts in ignition on key position