P3489 indicates an open circuit in the intake valve control actuator for cylinder 12, typically on engines equipped with a cylinder deactivation (variable displacement) system. The powertrain control module monitors the solenoid or actuator that controls the intake valve for that specific cylinder and has detected no electrical continuity. Because the code specifies 'open,' the problem is almost always electrical (broken wire, disconnected plug, or a failed solenoid coil) rather than a mechanical valve issue.
An open reading on the solenoid coil itself is the most common cause; the winding breaks internally and the circuit goes open, which the PCM detects immediately.
Chafed, heat-damaged, or broken harness wires between the PCM and the actuator create an open circuit and trigger the code on that single cylinder.
Oil-soaked or heat-cycled connectors frequently lose contact; an intermittent or fully open connection mimics a failed solenoid.
Cylinder deactivation relies on proper oil flow. Low pressure, sludged oil, or a restricted oil passage can prevent normal operation and may set this code on one or more cylinders.
A worn or stuck deactivation component on cylinder 12 can prevent the actuator from completing its stroke, sometimes reported by the PCM as a circuit anomaly.
Very unlikely. The PCM is the suspect only after the solenoid, wiring, connector, oil pressure, and mechanical components have all been ruled out by direct testing.
Usually not. The code points to a specific cylinder's intake valve control circuit being open, which in the vast majority of cases is caused by the solenoid itself, its wiring, or its connector. The PCM is one of the least likely causes and should only be considered after the solenoid, harness, connector, and oil pressure have all been tested.
Yes, in most cases the engine will continue to run normally on all cylinders, just without cylinder deactivation. Fuel economy will drop and the Check Engine Light will remain on. Persistent driving with the underlying cause uncorrected is generally fine short-term but should be diagnosed because oil-pressure related causes can affect multiple cylinders if ignored.
No. 'Open circuit' in the code description only tells you there is a break in the electrical path. That break can be the solenoid coil, the wire feeding it, or the connector. Direct resistance and continuity testing is required to tell which one.
Cylinder deactivation faults are reported per cylinder, so a single open wire, a single bad solenoid, or a single stuck component only sets the code on the affected cylinder. If multiple cylinders report similar codes, the problem is more likely shared, such as oil pressure or a common power/ground feed.