What does it mean?
P3426 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Cylinder 4 Deactivation/Intake Valve Control Circuit Performance . This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.
Symptoms
- MIL (check engine lamp) typically lights after the engine is fully warmed up
- A jolt, shudder or stumble when the engine changes between full and reduced-cylinder modes
- Rough idle and an intermittent cylinder 4 misfire
- Valve train noise that rises and falls with load and oil temperature
- Poorer fuel economy once the system disables itself
- The fault often follows the oil service interval, clearing after a change and returning later
Likely causes
- Low oil level or oil in poor condition, which robs the actuator of stable pressure
- Oil viscosity outside the specification for the engine, slowing the switching action
- Blocked or restricted oil passage, dirty screen, or sludge in the oil control valve
- Sticking or worn switching lifter / finger follower on cylinder 4
- Solenoid spool that moves slowly because of varnish, even though the coil resistance is correct
- Low oil pressure from a worn pump, faulty pressure control solenoid or excessive clearances
- Valve train wear that changes the mechanical timing the module measures
How to fix it
- Check oil level, oil condition and service history first, and confirm the correct viscosity
- Study freeze frame data for the oil temperature and load at which the fault set
- Command the solenoid on and off with a scan tool and observe whether the engine responds at all
- Take an actual oil pressure reading with a mechanical gauge, hot, at idle and off idle
- Remove the solenoid and check its screen and bore for varnish and debris; clean or renew it
- If the oil side is sound, inspect the cylinder 4 switching lifter and rocker components
- Perform an oil and filter change after the repair and verify over several drive cycles that the code does not return