P349D code meaning
Cylinder 6 Deactivation/Intake Valve Performance
Powertrain system Generic code P34xx codes Check engine light
What P349D means
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.
P349D 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 P349D
- Check engine lamp on
- Higher fuel use in light-load cruising
- Ticking from the engine valley
Common causes of P349D
- Most likelyLocking pins of the cylinder 6 lifters do not release
- PossibleOil solenoid of cylinder 6 sticking
- PossibleLow oil level or degraded oil
- Less likelyIntake leak or MAP sensor fault distorting the pressure pulses
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 P349D 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). |
| 9D | The exact fault in that area. |
What to do next
- Note P349D 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 P349D
What does P349D mean?
P349D means "Cylinder 6 Deactivation/Intake Valve Performance". P349D indicates that cylinder 6 drew in and pushed out air during events in which it should have stayed sealed. It is a generic code, so it means the same on every make.
Is it safe to drive with P349D?
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 P349D fail an emissions test?
Yes, it can. P349D 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 P349D to fix?
Difficulty: hard. A typical repair takes 0.5 to 14 hours of work. This is a job for a workshop.
Will P349D 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.