Diagnostic Aids

WARNING: This page is about a different car, the 1994 Oldsmobile Ninety-Eight and 1994 Buick Park Avenue. However, it is still accessible from the selected car via links, so may be relevant.

An intermittent may be caused by a poor connection, rubbed through wire insulation, or a broken wire inside insulation. Check for:

Backed out connector terminals or broken down insulation.
If connections and harness are okay, monitor voltage on spark reference circuit using DVOM while moving related wiring harness and connectors with engine idling. This may assist in isolating the malfunction.

Fig 1: Code P0321 Schematic (3.8L) Spark Reference Circuit

Fig 2: Code P0321 Flow Chart (3.8L) Spark Reference Circuit

Fig 3: Code P0321 Flow Chart