Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that the car's computer is having trouble controlling the opening and closing of the intake valves for cylinder 8. It's like one of the car's cylinders isn't working properly when it's supposed to be turned off.
The engine control module (ECM) is unable to control the deactivation of the intake valve for cylinder 8, affecting its performance.
P349F indicates a problem with the deactivation mechanism or performance of the intake valve on cylinder 8. This could be due to a mechanical failure, electrical issue, or a problem with the control system that manages cylinder deactivation.
• Engine misfire
• Reduced fuel efficiency
• Check Engine Light illuminated
• Faulty intake valve actuator
• Wiring issues in the valve control circuit
• Mechanical failure in the valve system
ECM: Engine Control Module, the computer that controls engine functions.
Intake Valve: A valve that allows air into the cylinder for combustion.
• Perform a visual inspection of the wiring and connectors for damage.
• Use a scan tool to check for additional trouble codes.
• Test the intake valve actuator for proper operation.
• Replace the faulty intake valve actuator.
• Repair or replace damaged wiring or connectors.
• Inspect and repair any mechanical issues with the valve system.
• OBD-II scanner
• Multimeter
• Mechanic's tool set
$200 - $500
Moderate
• Chevrolet Silverado
• GMC Sierra
• Cadillac Escalade
• Regular engine maintenance
• Timely oil changes
• Check wiring and connectors periodically
Engine Performance
• Avoid driving long distances until the issue is resolved.
• Consult a professional mechanic for a thorough diagnosis.
Check with your vehicle manufacturer for warranty coverage related to engine components.
This code has been reported in vehicles with cylinder deactivation technology, especially in those with higher mileage.
Moderate – It should be addressed soon to avoid further engine performance issues.
Driving with a deactivated cylinder can lead to increased emissions and potential engine damage.
• Engine at operating temperature
• Vehicle driven under normal conditions
The intake valve actuator for cylinder 8 is located on the engine, typically near the cylinder head.
Q: What happens if I ignore this code?
A: Ignoring this code can lead to reduced engine performance and potential damage over time.
Q: Can I drive my car with this code?
A: While you may be able to drive short distances, it's best to have the issue diagnosed and repaired to prevent further damage.
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Universal · Digital multimeter
A solid entry-level multimeter for voltage, continuity, resistance, and basic electrical troubleshooting.
Helpful for checking voltage drops, grounds, and basic circuit health when modules are not communicating.
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Universal · Wire connectors and repair kit
Useful when diagnosis points toward damaged wiring, corroded terminals, or connector repairs.
Useful if diagnosis points toward damaged connectors, wiring, or terminal repairs.
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Fitment Required · Vehicle-fitment part
Commonly relevant for misfire, ignition-efficiency, and some drivability-related repairs.
Misfire and ignition-related faults commonly involve spark plugs as part of the repair path.
Check the correct plug type, gap, and engine application for your vehicle.
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Fitment Required · Vehicle-fitment part
Relevant when the fault points toward ignition-coil performance or cylinder-specific ignition issues.
Some ignition faults involve coil performance or cylinder-specific coil problems.
Match the coil to your engine and confirm the failed component before ordering.
View options on AmazonThese parts may be related to this fault category, but a code by itself does not confirm exact fitment or guarantee that replacing a part will solve the problem.