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DTC codes / P34xx · Auxiliary emission controls / P349E

P349ECylinder 7 Deactivation/Intake Valve Performance

P349E indicates that the powertrain control module has detected a performance fault in the cylinder 7 deactivation system or its intake valve control, meaning the engine cannot properly switch cylinder 7 between full operation and deactivated mode. The computer monitors valve lift and timing via sensors and compares actual response to commanded state, setting the code when the expected change does not occur within a calibrated window.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyProfessional
AreaAuxiliary emission controls

Symptoms you may notice

  • Illuminated check engine light, often with no other noticeable symptoms
  • Rough idle or misfire-like shaking, especially when the engine is cold or under light load
  • Reduced engine power or a stumble during acceleration when cylinder deactivation activates
  • Audible ticking or tapping from the affected cylinder bank
  • Slightly worse fuel economy than usual
  • In rare cases, the engine may enter limp mode or disable cylinder deactivation entirely

Common causes, most likely first

  1. Faulty oil control solenoid or valve that regulates oil pressure to the cylinder 7 deactivation mechanism
  2. Sticking or failed hydraulic lifter or rocker arm for the intake valve on cylinder 7
  3. Clogged or restricted oil passage feeding the cylinder deactivation system
  4. Wiring damage or poor connection at the cylinder 7 deactivation solenoid or valve position sensor
  5. Failed intake valve actuator or collapsed lifter that prevents proper valve motion
  6. Low engine oil level or degraded oil that cannot maintain required hydraulic pressure
  7. Rarely, a faulty powertrain control module or software calibration issue

How to diagnose and fix it

  1. Check engine oil level and condition; top off or change oil if it is low or dirty
  2. Scan all modules for stored and pending codes, and record freeze-frame data to understand when the fault occurs
  3. Inspect the wiring harness and connectors at the cylinder 7 deactivation solenoid and valve position sensor for damage or corrosion
  4. Test the oil control solenoid with a bidirectional scan tool to command it on and off and listen for a click or observe valve state change
  5. Perform a cylinder leak-down or compression test on cylinder 7 to rule out mechanical valve or lifter failure
  6. Remove the valve cover and inspect the rocker arm, lifter, and pushrod (if applicable) for wear or sticking
  7. If the solenoid and wiring are good, replace the affected lifter or actuator assembly as per manufacturer procedure

Oil quality and hidden solenoid failures

  • Many technicians replace the cylinder deactivation solenoid only to find the real problem is a clogged oil passage or sludge buildup from neglected oil changes.
  • A stuck-open intake valve can cause a misfire that mimics an ignition coil fault, so always verify valve motion before replacing ignition components.
  • The code can set intermittently and may not illuminate the check engine light until the fault occurs multiple times, so pending codes are just as important.
  • On some engines, the deactivation system is disabled automatically when other faults (like low oil pressure) are present, so fix those first.
  • After repairs, a relearn or adaptation reset with a scan tool is often required to clear the code and restore proper operation.

Can I keep driving with P349E?

You can usually drive the vehicle short distances at moderate speeds, but avoid heavy acceleration or towing because the engine may misfire or lose power when cylinder deactivation is commanded. If the check engine light flashes or the engine runs very rough, stop driving and seek professional diagnosis.

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.

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