P349F code meaning
Cylinder 8 Deactivation/Intake Valve Performance
Powertrain system Generic code P34xx codes Check engine light
What P349F means
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.
P349F at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyHard
- Typical labor0.5 to 14 hours
- Clears after repairAfter a drive cycle
Symptoms of P349F
- Check engine lamp on after two trips
- Engine stays on all cylinders, fuel use rises
- Ticking noise at idle
Common causes of P349F
- Most 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
- Less likelyStored after a voltage dip at cranking, ECM software update needed
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
LifterValve trainCylinder deactivation solenoidEngine oil
What each part of P349F means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 3 | Mixed range: generic and manufacturer-specific codes. |
| 4 | Area: auxiliary emission controls (catalytic converter, EGR, EVAP). |
| 9F | The exact fault in that area. |
What to do next
- Note P349F and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P349F
What does P349F mean?
P349F means "Cylinder 8 Deactivation/Intake Valve Performance". P349F reports that cylinder 8 failed to go quiet when commanded. It is a generic code, so it means the same on every make.
Is it safe to drive with P349F?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P349F fail an emissions test?
Yes, it can. P349F is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P349F to fix?
Difficulty: hard. A typical repair takes 0.5 to 14 hours of work. This is a job for a workshop.
Will P349F clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.