P3460 indicates the engine control module has detected an abnormally high voltage in the control circuit for the cylinder 8 intake valve deactivation solenoid or actuator. This typically means the circuit is shorted to voltage, the solenoid has an internal fault, or a connection issue is causing the signal to read high.
The solenoid, lifter, or rocker actuator that disables the intake valve can develop an internal short or open, causing the control circuit voltage to read high and setting the code.
The wire running between the PCM and the cylinder 8 deactivation solenoid may be chafed, pinched, or melted, creating an unintended connection to a power feed.
Poor terminal contact, moisture intrusion, or corrosion at the solenoid or harness connector can create high resistance or an erratic high-voltage reading on the control circuit.
If the solenoid ground path is broken or has high resistance, the return side of the circuit can cause the control side to behave as if it is shorted high.
Although uncommon, a failed output driver inside the PCM could cause this code; it should only be considered after the solenoid, wiring, connectors, and grounds have been thoroughly tested.
It is generally safe for short trips, but the vehicle may run in full-cylinder mode and suffer reduced fuel economy. You should have it diagnosed soon to avoid possible valvetrain wear or related misfire issues.
Usually no. PCM failure is one of the least likely causes for this code. Most instances are caused by a faulty deactivation solenoid, a wiring short to voltage, or a connector problem.
A circuit high code means the voltage on the control circuit is higher than expected, often due to a short to power. A circuit low code means the voltage is lower than expected, often due to a short to ground or an open circuit.
It can contribute to rough running if the deactivation system is malfunctioning, but a dedicated misfire code usually points to ignition, fuel, or mechanical problems on that cylinder rather than the deactivation circuit itself.