P349C code meaning
Cylinder 5 Deactivation/Intake Valve Performance
Powertrain system Generic code P34xx codes Check engine light
What P349C means
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.
P349C 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 P349C
- Check engine lamp on
- Engine no longer skips cylinders, fuel use rises
- Vibration at light load
Common causes of P349C
- Most likelyLifter oil solenoid of cylinder 5 faulty, pole piece protruding
- PossibleLifters of cylinder 5 do not unlock
- Less likelyDirt in the oil blocking the solenoid or lifter bores
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Cylinder deactivation solenoidLifterValve trainEngine oil
What each part of P349C 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). |
| 9C | The exact fault in that area. |
What to do next
- Note P349C 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 P349C
What does P349C mean?
P349C means "Cylinder 5 Deactivation/Intake Valve Performance". P349C means that cylinder 5 stayed active although the engine computer had requested a skip. It is a generic code, so it means the same on every make.
Is it safe to drive with P349C?
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 P349C fail an emissions test?
Yes, it can. P349C 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 P349C to fix?
Difficulty: hard. A typical repair takes 0.5 to 14 hours of work. This is a job for a workshop.
Will P349C 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.