hey im about to put an air fuel gauge in but I don't know which wire on my o2 sensor is the signal wire. I have a blue wire, a white wire, and 2 black wires to choose from, I think it is the blue wire, but not sure, i want to be sure, before I hook up my air fuel gauge and break it or something else.

 

post pictures of the gauge and the wires coming out of it. is it wideband or narrowband? we'll work from there.

 

blue wire is the signal wire

 

You need to tap the White wire at the ECU for a narrowband a/f. Check out the thread in the HOW TO section for installing an SAFC. It gives you the ECU diagrams for MT and AT. If i remember correctly it was like the plug all the way to the right, 5th pin from the left on the top.....Check out the install thread