P3426 indicates that the powertrain control module detected an abnormal response from the intake-valve deactivation solenoid or control circuit for cylinder 4. During cylinder-deactivation operation, the PCM expects a specific electrical and mechanical feedback; this code sets when that feedback falls outside calibrated limits. It is generally a circuit or actuator fault rather than a general engine-performance failure.
The solenoid that switches the intake rocker or lifter for cylinder 4 can stick, open-circuit, short, or fail to move oil, causing the PCM to see incorrect feedback.
An open, short-to-ground, short-to-power, corroded, or high-resistance connection between the PCM and the solenoid can alter commanded voltage and current.
Deactivation systems depend on clean oil at proper pressure; low level, sludge, or wrong viscosity can prevent the solenoid or locking pin from engaging.
A stuck locking pin, worn rocker, faulty lifter, or related hardware can keep the intake valve from switching states and trigger a performance code.
If the system uses a switch or sensor to verify deactivation, a failed or stuck switch can falsely indicate a circuit performance problem.
A failing PCM driver or internal logic is uncommon; it should only be considered after the solenoid, wiring, oil, and mechanical causes have been ruled out.
The vehicle is usually drivable, but fuel economy may drop and the MIL will stay on; continuing to drive without repair can stress related components.
No. PCM failure is uncommon for this code; the solenoid, wiring, oil condition, or valve-train hardware are far more likely causes.
It can if the cause is low oil level, sludge, or wrong viscosity, but many cases require solenoid or wiring repair.
Generally no; repair usually focuses on the deactivation solenoid, harness, or specific valve-train component for cylinder 4.