Cylinder 4 Deactivation/Intake Valve Control Performance
Diagnostic trouble code P3426 indicates a performance issue with the cylinder 4 deactivation or intake valve control circuit. The powertrain control module (PCM) sets this code when it detects that the intake valve for cylinder 4 is not operating as commanded during the cylinder deactivation process.
While the vehicle can usually still be driven, a malfunctioning cylinder deactivation system can lead to poor engine performance, reduced fuel economy, and potential internal engine wear if left unaddressed.
Common symptoms
- Illuminated Check Engine Light
- Engine misfires or runs rough
- Decreased fuel efficiency
- Lack of engine power or hesitation during acceleration
- Vibration or shuddering when cylinder deactivation is commanded
Likely causes
- Low engine oil level or poor oil pressure
- Faulty cylinder 4 deactivation solenoid / intake valve control solenoid
- Dirty or degraded engine oil causing solenoid sticking
- Wiring or connector issues in the cylinder 4 deactivation circuit
- Mechanical failure within the variable valve timing or lifter assembly
- Faulty Powertrain Control Module (PCM) (rare)
What to check before replacing parts
Check the engine oil level and condition.
Look for: Ensure the oil is at the correct level and is not excessively dirty or sludged, as cylinder deactivation systems rely heavily on proper oil pressure and clean oil.
Inspect the wiring and connectors for the cylinder 4 deactivation solenoid.
Look for: Look for frayed wires, corroded pins, or loose connections that could cause an open or short circuit.
Test the cylinder 4 deactivation solenoid resistance using a multimeter.
Look for: Compare the resistance reading to the manufacturer's specifications; an out-of-range reading indicates a faulty solenoid.
Command the cylinder 4 deactivation solenoid on and off using a bi-directional scan tool.
Look for: Listen for an audible click from the solenoid and monitor engine RPM/data to verify the solenoid is mechanically responding to the PCM's command.
Perform an engine oil pressure test using a mechanical gauge.
Look for: Verify that the engine oil pressure meets the manufacturer's specifications, as low pressure can prevent the deactivation lifters from operating correctly.
This page explains the generic P3426 definition and is general reference information, not a diagnosis for your specific vehicle. Actual causes, severity, and repairs vary by make, model, engine, and mileage — always confirm with a scan tool and a qualified technician before replacing parts.
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