2

I was sent a Bosch universal o2 downstream sensor however their wiring diagram does not match that of the original sensor lead which I need to chop onto.

OEM is white, red, grey and black.

Bosch part is white, white grey and black.

Is there anyway I can test the wires or am I really going to have to do trial and error with whilst the cars turned on? There is no information online about a "white, red, grey and black" wiring sequence.

James
  • 21
  • 1
  • 2

1 Answers1

2

I think you are saying your replacement sensor has white, white, grey and black wires, which is the standard universal coding. White and white are heater wires, it doesn't matter whether hot or ground goes into which white wire. Black is signal, grey is sensor ground.

enter image description here

I cannot find a white, red, grey and black, but there is a purple one instead of red, which is Delphi 2 listed below. It's possible you've mistaken purple for red or the purple has faded. According to this sheet purple and white are the heater and heater ground, black is signal and grey is signal ground. If the brand of the sensor is Delphi you're probably good with that pinout.

You should test if those colors are right before you commit, although it does require the old sensor to be working at least partially. You can test the heater wires with a multimeter, looking for resistance - if you measure resistance you have the heater wires. If it's infinite resistance or zero then you don't have the heater wires and you need to try other combinations. You can verify this if the old sensor's heater is still working by hooking the heater wires to a 9 volt battery and it should heat up, although with an old sensor you never know - that may be the problem.

EDIT: as you say your sensor definitely has a red wire I would follow the above to determine the heater wires on the old sensor, then I would determine the signal and signal ground using the following method (please pay attention to safety here as heat is involved):

  1. Set your multimeter to voltage and connect the probes to the suspected signal and ground wires
  2. Heat up your lambda sensor end with a torch
  3. If you have the right wires then you will get a voltage reading, probably around 1V. If you get a positive voltage then the positive probe is connected to the signal wire and the negative to the signal ground. If you have a negative voltage it is the reverse

It could be that your old sensor's heater is broken, in which case you may get no resistance across any of the wires, in that case use the process above on all the wire combinations until you find the signal and ground, the remaining two will be the heater wires.

GdD
  • 18,048
  • 3
  • 38
  • 67