View Full Version : How to wire O2 sensor to Air/Fuel gauge?

Dan Pinder
04-09-2004, 01:36 AM
The turbo install is underway, but I am curious how to wire up my 3 wire air/fuel gauge to the 4 wire o2 sensor.

Any ideas?


Jay Stock E30
04-09-2004, 11:22 AM
umm, if I rember right, and yours is like mine, then 2 of those wires are +12 and a ground for the light, not connected to the o2. The last wire is the signal wire from the o2 sensor. I don't rember which wire off the o2 is the signal wire....If you can start the car its the wire that will return a value that is less than 1v. Lets see some pics eh?

04-09-2004, 03:58 PM
the red wire on the gauge is the power, connect that to a 12v ignition on source, the black is ground, and the purple is signal. connect the purple wire to the black wire on your o2 sensor. the o2 sensor should have 1 grey, 2 white, and 1 black wire.

Giga Shadow
04-10-2004, 02:16 AM
Or those pretty acurate?

04-10-2004, 11:04 AM
Tthe narow band o2 gauges? no. there not really accurate at all. they tell you if your richer than 14.7:1 or leaner than 14.7:1 and thats about it. you cannot accurately gauge exzactly how rich or how lean you actualy are.

although i have found that on an na vehicle, using an autometer air fuel gauge you want to tune WOT to the second green led. not the second to the last, but the third or foruth from the last. the second green leg into the portion that says "rich"

also, i may be incorect on the color of wire for the o2 signal. jason has his conected to his grey wire on his 02 sensor and it works. so, i have mine conected to the black wire, but i also have a mustang 02 sensor (they are all the same) and i think jason has a BMW 02 sensor that may have a slightly different wire color scematic.