What does it mean?
P3408 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Cylinder 1 Exhaust Valve Control Circuit High . 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
- Malfunction indicator lamp on and the valve control function disabled
- Valvetrain tick that does not change with the usual mode switching
- Misfire or rough running on the affected cylinder
- Loss of power and hesitation when the system would normally switch
- Fuel economy suffers because the module holds the engine in its default mode
- Fault may be intermittent and appear over rough roads
Likely causes
- Open circuit in the control or feed wire to the solenoid
- Solenoid coil open internally
- Loose or corroded terminal at the solenoid or PCM connector
- Control wire touching a permanently powered circuit after chafing
- Blown fuse feeding the solenoid supply
- Broken conductor at a flex point in the engine harness
- Failed driver stage in the PCM
How to fix it
- Check engine oil level and condition, then read all codes and note freeze frame data
- Measure the solenoid winding resistance; infinite resistance confirms an open coil
- Check continuity from the PCM pin to the solenoid pin, and voltage drop on the supply side
- With the key on and the solenoid unplugged, check the control wire for battery voltage
- Perform a terminal drag test on both the solenoid and module connectors
- Repair the open circuit, or the short to voltage where one is found, and re-secure the harness
- Replace the solenoid, then confirm the system cycles correctly on a road test