86 vs 90 O2 Sensors

Bullitt

Packin' Heat
Founding Member
Jan 13, 2000
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Houston, TX
Short time ago one of the O2 sensor plugs got onto the headers and melted. I bought some harness extenders (for a 90) in order to splice in new connectors.

When I got them home though, realized that the "90" O2 harness I had has the '86-earlier style plug (3 prong) instead of the 87 and later 4 prong plug. No codes were thrown and driveability seems ok. I am running an A9P computer.

Based on wiring diagrams, there doesn't appear to be any difference (only 3 of the 4 wires appear to be in use) so it doesn't seem like it'd be a problem to splice in the 4 prong connector.

My questions is though - did I damage something using an older sensor? Any issue foreseen swapping to the newer style sensor and plug?

Any help would be appreciated! Thanks!