Thread: a/f gauge wiring question

i just got an a/f gauge from another member, (narrowband) and it uses the stock o2 sensor wiring..previous member had it in a b13 which only had 1 o2 sensor (obd1) my car is obd2 and has 2 o2 sensors..my question is what o2 sensor signal wire do i tap into? upstream (1st) or the downstream (2nd) one?

thanks

You need to use the downstream one. Otherwise you'll only see one cylinder. At the same time though, I think narrowband meters are useless.

You need the pre-cat one since catalytic converters mess with the readings.

In a car in good repair reading off 1 cylinder is ok. That's how most OEMs used to do it.