P349DCylinder 6 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
- P349D indicates that cylinder 6 drew in and pushed out air during events in which it should have stayed sealed. The test logic rests on a simple effect: every intake stroke leaves a dip in manifold pressure, so a resting cylinder should leave none. Ford's patent US8667835B2 and Delphi's US7314034B1 describe tracking these pulses event by event. GM applies the idea to its L84 and L87 V8s with filtered manifold pressure, 22 failures out of 25, Type B. The older GM AFM V8s also switch off cylinder 6, but there faults surface through the bank code P3400. Likely causes are a lifter whose locking pins do not release, a sticking solenoid or poor oil. P3442 is the control-performance sibling, P0306 the misfire code of this cylinder.
- What you may notice
- Check engine lamp on
- Higher fuel use in light-load cruising
- Ticking from the engine valley
- Likely causes
- LikelyLocking pins of the cylinder 6 lifters do not release
- PossibleOil solenoid of cylinder 6 sticking
- PossibleLow oil level or degraded oil
- RareIntake leak or MAP sensor fault distorting the pressure pulses
- 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.