the Apexi turbo timer A/F is not displaying anything on the screen just the two lines i do wait until the car gets warm too. I think I put the O2 senson in the wrong place. What one should i us

rear
- Rear o2 sensor
- heater signal

front
- front o2 heat sensor
- a/f sensor +
- a/f sensor -
- a/f sensor shield

Thanks