P3406Cylinder 1 Exhaust Valve Control Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- Where an engine controls the exhaust valves of cylinder 1 separately, P3406 would mean the exhaust side does not follow the command although the circuit checks pass. No manufacturer documents this code publicly. Ford holds a patent that detects an exhaust valve still opening after deactivation through pressure changes in the exhaust, and a GM patent, using one shared control valve, has the exhaust valves deactivate and also reactivate before the intake valves, so a lagging exhaust side is a real failure mode. Production systems from GM and Ford instead check the whole cylinder (GM P3498, Ford P3402). Electrical faults on this channel are P3405, P3407 and P3408; if the cylinder keeps pumping exhaust, the driver may feel roughness.
- What you may notice
- Check engine lamp on
- Rough running or vibration in reduced-cylinder mode
- Cylinder deactivation suspended
- Likely causes
- PossibleInsufficient or degraded oil delays exhaust-side switching
- PossibleExhaust lifter or rocker of cylinder 1 not latching or unlatching
- RareExhaust valve actuator sticking
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €100 – €3,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.