The Catera 3.0L V6 is equipped with a Distributorless Ignition System (DIS). In this ignition system, both ends of each of the three ignition coils are connected to a spark plug. A pair of cylinders share one coil in the following arrangement: 1 and 4, 2 and 5, 3 and 6. Each coil is connected to spark plugs on companion cylinders, i.e., on top center at the same time. One cylinder is on the compression stroke when the other one is on the exhaust stroke.

When the coil discharges, both plugs fire at the same time by using the engine block in order to complete the electrical circuit. The cylinder on the compression stroke is called the event cylinder and the cylinder on the exhaust stroke is the waste cylinder. The two cylinders share the energy that is available from the ignition coil in order to fire both spark plugs. This method of ignition is called the waste spark ignition.

The Catera DIS system consists of the coil pack and the ECM. There is no separate ignition control module. The ECM performs all of the ignition control module functions. The Ignition Coil assembly is powered by an ignition feed circuit. The remaining three wires go to the ECM and are the Ignition Control (IC) circuits. The ECM causes a spark to occur by pulsing an IC circuit, which triggers an ignition coil and fires the appropriate pair of spark plugs. The sequencing and the timing are ECM controlled. The ECM uses input from the Crankshaft Position (CKP) Sensor, the Camshaft Position (CMP) sensor and the Knock Sensors in order to appropriately control the ignition system operation.