P349FCylinder 8 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
- P349F reports that cylinder 8 failed to go quiet when commanded. California's OBD rule requires makers to analyse every plausible hydraulic or mechanical failure of variable valve systems and mentions, among its examples, a lift-mechanism pin of one cylinder that will not shift; codes like this one follow from that duty. GM implements it for cylinder 8 on its L84 and L87 DFM V8s: filtered manifold pressure above the deactivation threshold in 22 out of 25 chances, rated Type B, so the lamp lights on the second faulty trip. GM's LT2 and LTA engines also rest cylinder 8, but no public GM table assigns P349F to them. Typical causes are a lifter stuck in its locked state, a failing oil solenoid or sludge. P3458 is the control-side code, P0308 the misfire code.
- What you may notice
- Check engine lamp on after two trips
- Engine stays on all cylinders, fuel use rises
- Ticking noise at idle
- Likely causes
- LikelyLifter of cylinder 8 stuck in its locked state
- PossibleWeak or sticking oil solenoid of cylinder 8
- PossibleSludge or debris in the lifter oil passages
- RareStored after a voltage dip at cranking, ECM software update needed
- 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.