i never installed one in xb yet... but from wat i remember autometer air/fuel ratio gauge has 3 wires... red black and purple... i think red is 12V black is ground and purple is signal from your O2 sensor.... you have to find out which wire is the right one O2 sensor has 3 or 4 wires some cars have 5 wires and it has power, ground, signal(high and low) for 4 wires... autometer tells you to tap it onto signal(high) wire... just tap on anything and you will find one that works... it doesn't messup your car or gauge... i did that to my celica like 2 years ago... and i found right wire to work with...well good luck with it...