P3418Cylinder 3 Deactivation/Intake 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
- P3418 is meant for a cylinder 3 deactivation that is wired correctly yet does not respond as requested: the cylinder keeps breathing when it should rest, or fails to come back. No manufacturer documents this code publicly. GM tests the hardware of cylinder 3 under its own code P349A; bulletin 20-NA-204 for the 2021 L84 and L87 notes that a voltage dip during cranking can briefly disable the outputs and set that code without a real fault. Honda shows the same failure pattern in another form: in bulletin 13-055 excess cold-start oil pressure pushed cylinders 1 to 4 into cut mode uncommanded, logged as P3400/P3497 with misfires. Circuit faults belong to P3417, P3419 and P3420. Expect rough running and a misfire code.
- What you may notice
- Misfire code for cylinder 3 (P0303)
- Shudder when the engine changes between modes
- Check engine lamp on
- Likely causes
- LikelyLow oil level, wrong viscosity or aged oil
- PossibleLifter or rocker of cylinder 3 not locking or unlocking
- PossibleCylinder 3 control valve sticking or its screen blocked
- RareOil pressure too high or too low for the switching window
- 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.