P3408 indicates that the engine control module has detected a high voltage condition in the exhaust valve control circuit for cylinder 1. This circuit drives the variable valve timing (VVT) solenoid that adjusts exhaust valve timing, and a high signal typically means a short to power or an open‑circuit fault in the solenoid or its wiring.
The solenoid internal winding may be shorted, causing the control circuit to read a high voltage.
A damaged or pinched wire in the solenoid harness can create a direct path to power, raising the circuit voltage.
Poor contact can cause the control module to sense an abnormal high voltage on the driver line.
If the ground return is broken, the driver may pull the line high, registering as a high‑voltage fault.
A defective output driver inside the ECM can stuck high; this is rare and should be considered only after other causes are ruled out.
No. The ECM driver fails rarely; the majority of cases are due to the solenoid, wiring, or connector issues.
Clearing the code will turn off the light temporarily, but the underlying fault will likely return and can cause drivability problems or increased emissions.
A basic OBD‑II scan tool, a digital multimeter for resistance and voltage checks, and a wiring diagram for the specific vehicle.
P3408 is specific to the exhaust valve control circuit for cylinder 1; other cylinders have separate codes if they experience similar faults.