o2 sensor

I'm trying to test my o2 sensor and the book said backprobe o2 sensor to attach multimeter. I'm not sure what backprobe means can any one help:banghead:

Not sure if you already got this one figured, but it just means you have the o2 sensor plugged in as normal and you take the multimeter's prongs and stick them into the wire's socket from the back, ie backprobe it, so you don't have to cut anything. If the multimeter's probes/prongs are too thick you can use pins or needles in the back of the wiring socket then touch the probes to those.