how do i install a air fuel ratio gauge

[OSM e30]

i was wondering if there is a DIY on installing a air/fuel gauge on my car? i kno it connects to the o2 sensor but whichs wires do i hook it up to, i have a 89 325i

[backtrail69]

There is little to no point to hook one up unless you have a wideband 02 sensor.

[Erick]

There is little to no point to hook one up unless you have a wideband 02 sensor.

^ What he said.

[xLibelle]

completely agree

[Garageaholic]

They are right, but if you wanted to know, the purple wire is signal. then you have your positive and ground...

I have one hooked up only to tell if I am idling at the correct 14.7ish. That's all. If i'm not, i know something is wrong. The A/F will tell me if its correct by quickly swishing back and forth between lean and rich.... but i may sell mine bc i dont really even use it that much.

[franco90]

Frank
where do you connect the purple wire?. i mean in the engine bay