01 How to Change a Car Tire • 02 How Adaptive Cruise Control Actually Works • 03 Drivers Are Only Just Discovering Why Their Cars Randomly S… • 04 The Right Way to Charge EV Batteries: Lessons from Stanford… • 05 Why Resetting ECU Without Fixing Root Cause Always Backfires • 06 Why Crankshafts Matter in Converting Power to Rotation • 07 The Real Reason SUVs Are Dominating the Market • 08 After 66 Years, Someone Finally Fixed the Seatbelt's Bigges… • 09 A Watch Collector Spent $49.4 Million on Four Rolexes and t… • 10 Why Some Engines Run Better After Being Driven Hard Occasio… •

DTC codes / P34xx · Auxiliary emission controls / P3426

P3426Cylinder 4 Deactivation/lntake Valve Control Performance

P3426 indicates that the powertrain control module (PCM) has detected a performance fault in the cylinder 4 deactivation or intake valve control circuit, meaning the valve did not respond as commanded within the expected time or position. The PCM monitors the circuit and valve response, and when the actual state does not match the commanded state, it stores this code and may disable the cylinder deactivation feature.

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

Symptoms you may notice

  • Illumination of the check engine light, often with no other noticeable symptoms
  • Rough idle or vibration when the engine transitions into cylinder deactivation mode
  • Reduced fuel economy because the engine may stay in full-cylinder mode
  • A slight hesitation or stumble during light-throttle cruising
  • In some cases, a loud ticking or tapping noise from the affected cylinder bank
  • The driver may notice the engine does not enter eco or fuel-saving mode as usual

Common causes, most likely first

  1. Faulty cylinder deactivation solenoid or control valve on cylinder 4
  2. Damaged or chafed wiring in the deactivation valve control circuit
  3. Corroded or loose electrical connector at the deactivation solenoid
  4. Sticking or mechanically failed intake valve control actuator
  5. Low engine oil level or degraded oil causing poor hydraulic response
  6. Failed oil control valve or lifter for the deactivation mechanism
  7. PCM software calibration issue or internal driver fault (less common)

How to diagnose and fix it

  1. Check engine oil level and condition; top off or change oil if degraded
  2. Inspect the deactivation solenoid connector and wiring for damage or corrosion
  3. Measure resistance of the deactivation solenoid and compare to specification
  4. Test the control circuit for power and ground signals from the PCM
  5. Remove and inspect the deactivation solenoid for debris or sticking
  6. Perform an active test of the cylinder deactivation system with a scan tool
  7. If all electrical and hydraulic checks pass, replace the faulty valve control actuator or lifter

Oil quality and hidden wiring faults

  • A low oil level or heavily contaminated oil is a frequent cause of this code because the deactivation system relies on clean, pressurized oil to move the locking pins; always verify oil condition before replacing parts.
  • The wiring harness to the deactivation solenoid often rubs against the valve cover or intake manifold, causing intermittent shorts that set P3426 only under certain engine movements.
  • A stuck-open intake valve control actuator can mimic a failed solenoid, so testing the mechanical movement of the valve is as important as electrical checks.
  • This code does not always mean the solenoid is defective; a clogged oil passage or a failing oil pump can reduce hydraulic pressure enough to trigger the performance fault.
  • After repairs, the PCM may need a relearn or adaptation reset for the cylinder deactivation system to clear the code and restore normal operation.

Can I keep driving with P3426?

You can usually continue driving with P3426, but avoid heavy loads and sustained high speeds because the engine may remain in full-cylinder mode and consume more fuel. Have the fault diagnosed soon to prevent potential damage to the valve train or catalytic converter from unburned fuel.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

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

Running on fumes Free guides aren't free to make. Top up the tank. Any amount, one time. Fuel the Garage