What does it mean?
P3425 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Cylinder 4 Deactivation Solenoid Control Circuit .
Symptoms
- MIL (check engine lamp) on and cylinder deactivation disabled
- Fuel consumption climbs because the engine always runs on all cylinders
- Rough idle and vibration if the cylinder 4 valve stays collapsed
- Ticking or clacking noise from the cylinder head
- Cylinder 4 misfire, sometimes with matching misfire codes
- Slightly softer throttle response than usual
Likely causes
- Solenoid connector unlatched, backed out or with a terminal displaced in its housing
- Broken control wire between the module and the valve lifter oil manifold
- Engine oil migrating up the harness and insulating the terminal faces
- Open winding inside the cylinder 4 deactivation solenoid
- Blown fuse or open supply feed shared by the deactivation solenoids
- Harness damage under the intake manifold, often from an earlier repair
How to fix it
- Read and note freeze frame data before clearing anything
- Unplug the cylinder 4 solenoid and inspect the terminals for oil film, corrosion and push-back
- Measure the coil resistance across the solenoid pins; an infinite reading confirms an open winding
- Check continuity of the control wire all the way to the module connector
- Confirm supply voltage at the connector with the key on and check the relevant fuse
- Wiggle the harness while monitoring resistance to expose an intermittent open
- Repair the wire or terminal or fit a new solenoid, then command the output with a scan tool to confirm the circuit now draws current