- 1987 Factory-verified
not with W02 or WE2; gnttype.org's 1987 option sheet; the kit page prints CO4; shared G-body code, cited from the Monte Carlo kit
GM Heritage factory kit — 1987 Chevrolet Monte Carlo, p.88.
C04 Factory-verified
Also documented for Chevrolet
Documented applications
This page aggregates every documented appearance of C04 in the Buick reference. Confidence and citations are shown per application — the same code can be better documented in one year than another.