Failed or sticking cylinder deactivation solenoid or oil control valve; Worn or collapsed hydraulic lifter for the intake valve on cylinder 5; Low engine oil level or degraded oil causing insufficient hydraulic pressure; Clogged oil passage or screen feeding the deactivation system; Faulty intake valve actuator or rocker arm assembly; Wiring damage or poor electrical connection at the deactivation solenoid; Mechanical valve train wear, such as a worn camshaft lobe or valve spring

DTC codes / P34xx · Auxiliary emission controls / P349C

P349CCylinder 5 Deactivation/Intake Valve Performance

Q: What does code P349C mean?

Cylinder 5 Deactivation/Intake Valve Performance. P349C indicates that the powertrain control module has detected a performance fault in the cylinder 5 deactivation or intake valve system, meaning the valve did not respond as expected when commanded. The computer monitors valve lift or intake airflow and sets this code when the measured response falls outside the expected range during activation or deactivation.

P349C indicates that the powertrain control module has detected a performance fault in the cylinder 5 deactivation or intake valve system, meaning the valve did not respond as expected when commanded. The computer monitors valve lift or intake airflow and sets this code when the measured response falls outside the expected range during activation or deactivation.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyProfessional

AreaAuxiliary emission controls

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
Rough idle or misfire-like shaking, especially when the engine transitions between full and reduced displacement
Reduced engine power or a sudden loss of acceleration when cylinder deactivation is commanded
Audible ticking or tapping from the valve cover area on the affected bank
Poor fuel economy or increased emissions due to improper cylinder sealing
In rare cases, the engine may enter limp mode to protect the valvetrain

Common causes, most likely first

Failed or sticking cylinder deactivation solenoid or oil control valve
Worn or collapsed hydraulic lifter for the intake valve on cylinder 5
Low engine oil level or degraded oil causing insufficient hydraulic pressure
Clogged oil passage or screen feeding the deactivation system
Faulty intake valve actuator or rocker arm assembly
Wiring damage or poor electrical connection at the deactivation solenoid
Mechanical valve train wear, such as a worn camshaft lobe or valve spring

How to diagnose and fix it

Check engine oil level and condition; top off or change oil if it is low or dirty
Scan all modules for stored and pending codes, and verify oil pressure with a mechanical gauge
Inspect the wiring and connector at the cylinder 5 deactivation solenoid for corrosion or damage
Command the cylinder 5 deactivation solenoid on and off with a scan tool and observe valve lift or intake airflow response
Test the solenoid resistance and compare to specification; replace if out of range
Remove the valve cover and inspect the lifter, rocker arm, and camshaft lobe for wear or sticking
Clean or replace clogged oil passages or screens, and recheck system operation after repair

Oil quality and pressure drive this code

A common oversight is ignoring oil maintenance; degraded oil or a low level can prevent the hydraulic lifter from collapsing or extending, setting P349C without any hard part failure.
The code does not always mean the solenoid is bad; a stuck lifter or clogged oil passage can produce the same performance fault, so testing oil pressure and flow is essential before parts replacement.
On many engines, the deactivation system shares oil with the variable valve timing system, so a VVT fault or sludge buildup can indirectly trigger P349C.
Intermittent faults often appear only when the engine is cold or under light load, so a road test with a scan tool recording valve activity is more reliable than a static inspection.
After repairs, the adaptive learning for the deactivation system may need to be reset with a scan tool to prevent the code from returning immediately.

Can I keep driving with P349C?

Driving with P349C is generally safe for short distances, but avoid heavy acceleration or sustained high speeds because the engine may be running on fewer cylinders and could overheat or damage the valve train. Have the vehicle diagnosed promptly, especially if you notice rough running or power loss.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.