P349CCylinder 5 Deactivation/Intake Valve 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
- P349C means that cylinder 5 stayed active although the engine computer had requested a skip. GM documents it for its Dynamic Fuel Management V8s (L84 with 5.3 l, L87 with 6.2 l), where every cylinder may be skipped; the classic AFM V8s rest only cylinders 1, 7, 6 and 4. Detection compares filtered manifold pressure with a deactivation threshold, and a Type B code follows after 22 failures out of 25. For 2019 Silverado and Sierra trucks, GM's PIP5584 blames the lifter oil solenoid of the affected cylinder: replace it and inspect the remaining solenoids for a pole piece that stands proud of the surface. Wiring faults for cylinder 5 appear as P3433, P3435 and P3436. The driver sees the lamp and pays with higher fuel use.
- What you may notice
- Check engine lamp on
- Engine no longer skips cylinders, fuel use rises
- Vibration at light load
- Likely causes
- LikelyLifter oil solenoid of cylinder 5 faulty, pole piece protruding
- PossibleLifters of cylinder 5 do not unlock
- RareDirt in the oil blocking the solenoid or lifter bores
- 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 – €4,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.