O2 sensor locations on three-way catalytic converter; G3/1 downstream, G3/2 upstream TWC on Smart chassis 450/451/452/454.

Rear view of Smart car with callout showing O2 sensor positions on catalytic converter assembly.

View full-size image ↗

See all Powertrain figures for the Fortwo (450), or browse the full figure library. Part numbers and callouts are community-sourced and cross-referenced against the manuals — confirm with your VIN before ordering.