o2 sensor signal wire

hey guys whats going on im putting in an air fuel guage but i wanted to make sure which wire was the signal wire in the o2 sensor that is in the engine bay i have a feeling its the purple one but i want to make sure i have a 97 grand prix se non supercharged i would appreciate a quick answer thanks guys

yep, purple one. it'd be easier and more peace of mind though to consider buying the A/F pigtail.