I am putting a 3 wire Bosch O2 sensor in tonight and trying to figure out how to wire this thing properly. It has two white wires and one black. The black wire I found is the signal wire and the two white wires are for the heater. Now the question is where do I plug the two white heater wires in? Is one a constaint 12v current and the other is ignition? If so does it matter which is which? or are they both sapose to be hooked to a ignition 12v so it is only powered when the car is turned on? Not sure how O2 sensors work, install MANY radios and other electronics but this thing I am not sure of and dont want to have it pluged up wrong.

Come on rotary fanatics lets see what cha got ;]

Mike

 

I think one white is ground and the other white is 12v accessory. I could be wrong, so I will try to get a more definitive answer for ya.

 

Here is where I got the info i know so far.... but doesnt really say how it should be wired... only states that you should match the stock wireing. Which in our case we dont run 3 wire O2s. Thanx evita, but there is no ground. I believe the unit is using the exhaust as its own ground.

 

Rotaries dont use heated O2 sensors.(except maybe the RX-8)
If your adapting to use a heated O2,the only benefit will be that the ECU will begin close looping sooner due to the O2 sensor heating up quicker.(youll never notice the difference)
Plus,with the rotaries natural hot exhaust, the sensor should get up to temp very quickly by itself. All you need is to hook up the black wire.

 

On that note I am using the 3 wire to use a Autometer A/F gauge... I know I know...should get a wideband, but this is just to get the car going and give me a rough idea on how rich im running untill i dyno it. Went with a 3 wire just to help with readings. Seeings this O2 is designed to use the heater element I would rather plug it up rather than allowing the exhaust to heat it up. The 3 wire was just as expensive as the single wire so I said what the hell and got this one. Any ideas on how to wire it properly?

 

I forgot to post the link i was refering to on my other post here it is.... http://www.boschusa.com/images/OxygenSensorInstall.pdf

 

One goes to +12 with the key on, one goes to ground. It's the oxygen sensor heater and as the PDF and others have said, it doesn't matter which is which... Heaters have no polarity...

Besides, if we told you it DOES matter, how would you distinguish the white wire from the other white wire?

When I build a bomb, all the wires will be the same color!

Anyhow... those wires are for the heater. The exhaust is used for SIGNAL ground...

 

well.. since the subject's up.. would the bosch universal o2 sensor be alright to use? my wire broke off of my current one, and i'm not sure how old it is to begin with (RB header from ebay)...