OBD-II code P3484 indicates the engine control module has detected an abnormally high voltage signal in the intake valve deactivation control circuit for cylinder 11. This circuit typically operates a solenoid that engages or disengages the intake valve's active oil-controlled lifter, allowing the engine controller to deactivate that cylinder during light-load conditions. A 'high' reading usually means the controller is seeing an open circuit, excessive resistance, or a short to voltage rather than the expected grounded pulse-width-modulated signal.
The solenoid itself is the most common failure point. Internal winding opens, shorts, or carbon-contaminated oil causes it to stick, producing a high-voltage / open-circuit condition the PCM reports as P3484.
Chafed insulation, broken leads near the valve cover, oil-soaked or heat-hardened connectors, and spread or backed-out pins in the harness connector are frequent causes of an open or high-resistance circuit.
The deactivation system is hydraulically actuated. Sludge, wrong oil viscosity, a restricted oil passage, a weak oil control valve, or low oil level can prevent the lifter from latching, causing the electrical signature of the circuit to read abnormally high.
A mechanically failed lifter cannot hold the deactivation state, and the resulting abnormal movement of the internal pin can mimic or cause an open-circuit reading at the solenoid.
Shared grounds, splices, or the PCM-side driver circuit developing high resistance can pull the sensed voltage above the expected range, falsely setting the code.
An internal driver issue in the PCM that controls cylinder 11's deactivation solenoid is possible but uncommon; it should only be considered after the solenoid, wiring, oil pressure, and lifter have all been ruled out.
Yes, in most cases the vehicle will continue to run, usually with slightly reduced fuel economy and a rougher idle. The cylinder deactivation system will simply be disabled, and the affected cylinder will fire continuously. The code should be diagnosed reasonably soon to prevent secondary issues such as oil consumption or uneven valvetrain wear.
No. P3484 is almost never caused by a bad PCM. The vast majority of confirmed repairs are a faulty cylinder deactivation solenoid, a damaged harness/connector, an oil-pressure or oil-flow problem, or a failed lifter. The PCM should be suspected only after all of those have been ruled out with test results, not as a first guess.
It can be. A deactivation solenoid that fails to release the lifter, or one that won't engage it, can leave cylinder 11 running rich or contribute to a misfire, which may set additional codes. Fixing the underlying P3484 cause typically clears the related codes as well.
Sometimes, briefly, if the fault was intermittent (for example, a cold-start oil-pressure blip). It will usually return once the same condition is detected. A proper repair followed by a code clear with a scan tool is the reliable way to confirm the fix.