P3408Cylinder 1 Exhaust Valve Control Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- If an engine has its own actuator for the exhaust valves of cylinder 1, P3408 marks a control circuit that reads high, usually a short to battery voltage. No manufacturer documents this code publicly. For comparison, GM checks the intake-side P3404 with the driver switched on and flags under 0.5 ohm to supply. A GM patent application switches intake and exhaust valves together through one shared hydraulic valve, exhaust side first, and describes no separate exhaust channel either. With one solenoid per cylinder, as on GM's DFM, the code is not needed. Siblings: P3405 open, P3406 function, P3407 short to ground; P3404 is the intake-side equivalent.
- What you may notice
- Check engine lamp on
- Cylinder deactivation disabled
- Likely causes
- PossibleControl wire shorted to a supply voltage
- PossibleShorted coil in the exhaust valve actuator
- RareOutput stage fault in the engine control module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €60 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.