12569429

AC DELCO FRONT O2 SENSOR FITS LH & RH LS GEN III/IV ENGINE

Replacement GM O2 sensor

Suites VZ VE VF V8 Models. Compatible with E38 ECUs

Square plug type (see pics) 

This is the first (upstream) sensor. This is the one you will require for tuning. Suits LS conversions running the standard E38 E40 ECUs