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P3425 Cylinder 4 Deactivation/Intake Valve Control Circuit/Open GuideMechanic.Com Modern engines are increasingly reliant on advanced control systems to improve efficiency and reduce emissions.
One such innovation is cylinder deactivation technology, also known as Displacement on Demand (DoD), Active Fuel Management (AFM), or Variable Valve Timing (VVT) depending on the manufacturer.
This technology disables selected cylinders during low-load conditions, such as highway cruising, to improve fuel economy.
However, when there’s a malfunction in one of these systems, your vehicle’s Powertrain Control Module (PCM) or Engine Control Module (ECM) stores a diagnostic trouble code (DTC), such as P3425 – Cylinder 4 Deactivation/Intake Valve Control Circuit/Open.
Understanding what this code means, what causes it, and how to fix it is essential for maintaining your vehicle’s performance and longevity.
See Also: P3426 Cylinder 4 Deactivation/Intake Valve Control Circuit Performance
P3425 Cylinder 4 Deactivation/Intake Valve Control Circuit/Open
What Does Code P3425 Mean?
DTC P3425 is defined as “Cylinder 4 Deactivation/Intake Valve Control Circuit/Open.” This code indicates that the ECM/PCM has detected an open circuit in the electrical path responsible for controlling the intake valve actuator or solenoid on cylinder 4, which is used during cylinder deactivation.
An “open circuit” means that the electrical current cannot flow through the intended path—similar to how a broken wire in a lightbulb prevents it from turning on.
In this case, it means that the intake valve for cylinder 4 cannot be properly controlled by the ECM, so the cylinder deactivation system may fail to engage or disengage as intended.
How Cylinder Deactivation Works
In engines with DoD or AFM systems, specific cylinders are temporarily deactivated under light engine loads. This is done to reduce fuel consumption by minimizing the number of active combustion events. The system works by:
- Disabling valve movement: Special solenoids controlled by the ECM redirect oil pressure to hydraulic lifters, which collapse and prevent the intake and exhaust valves from opening.
- Controlling the fuel injection: The fuel injectors are turned off for the deactivated cylinders.
- Restoring full operation: Under heavier load conditions, the system re-engages the valves and fuel injectors.
Each cylinder has an intake valve control solenoid, and if the ECM detects an open circuit on cylinder 4’s intake side, it sets code P3425.
P3425 Cylinder 4 Deactivation/Intake Valve Control Circuit/Open
Symptoms of P3425
Depending on the severity of the issue, the following symptoms may appear:
- Check Engine Light (CEL) illuminated
- Engine misfire, especially under light load
- Rough idling or hesitation
- Decreased fuel efficiency
- Reduced engine performance
- Excessive engine noise, such as ticking
- Hard starting or stalling in extreme cases
Sometimes, the only indication of the issue is the check engine light with no noticeable performance symptoms, especially during early stages.
Common Causes of P3425
Several potential issues can cause code P3425 to appear. These include:
Faulty Cylinder 4 Intake Valve Control Solenoid
A defective or stuck solenoid cannot properly engage or disengage the valve, causing an open signal.
Broken or Disconnected Wiring
Damaged, frayed, or broken wires can disrupt the signal between the ECM and the solenoid.
Loose or Corroded Connectors
Poor electrical connections can mimic the symptoms of an open circuit.
Low or Dirty Engine Oil
Oil pressure plays a crucial role in the activation of the valve control system. Insufficient or dirty oil can impair operation.
Clogged Oil Passages
Sludge buildup or debris can block oil flow to the lifters and solenoids.
Faulty ECM/PCM
In rare instances, the engine control module itself may be malfunctioning.
P3425 Cylinder 4 Deactivation/Intake Valve Control Circuit/Open
Diagnosing Code P3425
Proper diagnosis is critical before replacing any components. Follow this step-by-step guide to troubleshoot the issue:
1. Scan for Codes
Use a professional OBD-II scanner to confirm the presence of P3425.
Note any accompanying codes, such as misfire or other valve control codes, which may indicate a broader issue.
2. Inspect Engine Oil
Check the oil level and quality. Old or dirty oil can impede valve operation.
Perform an oil change with the correct viscosity if needed.
3. Perform a Visual Inspection
Examine the wiring and connectors leading to the cylinder 4 intake valve control solenoid.
Look for signs of wear, damage, corrosion, or disconnection.
4. Test the Solenoid
Disconnect the solenoid and use a digital multimeter to measure resistance.
A typical solenoid will have a resistance value within a specific range (often 10–20 ohms). An open circuit will show infinite resistance.
5. Check for Power and Ground
With the key on, verify that the solenoid’s connector has proper voltage and ground using a multimeter.
No voltage indicates a possible break or open in the circuit.
6. Check ECM Signals
If everything else checks out, use a scan tool or oscilloscope to monitor ECM outputs.
Compare readings with service manual specifications.
P3425 Cylinder 4 Deactivation/Intake Valve Control Circuit/Open
Recommended Repairs for P3425
Once the root cause is identified, one or more of the following actions may resolve the issue:
Replace Cylinder 4 Intake Valve Control Solenoid
If the solenoid fails resistance testing or is stuck.
Repair or Replace Wiring and Connectors
Fix broken wires, reconnect loose connectors, or clean corroded contacts.
Perform an Oil and Filter Change
Dirty oil can block oil passages, affecting solenoid operation.
Flush Oil Passages
If sludge or debris is suspected, clean the system using manufacturer-approved procedures.
Reprogram or Replace the ECM
Only if diagnostics confirm that the control module is faulty.
After making repairs, clear the DTC using an OBD-II scanner and test drive the vehicle to confirm that the code does not return.
P3425 Cylinder 4 Deactivation/Intake Valve Control Circuit/Open
Preventing P3425
The best way to prevent code P3425 and related issues is through routine maintenance and early detection:
- Change engine oil regularly, following the manufacturer’s service schedule.
- Use the correct oil viscosity and type to ensure optimal pressure and solenoid function.
- Inspect wiring and connectors periodically, especially in high-heat or vibration-prone areas.
- Avoid prolonged idling, which can accelerate oil contamination.
- Address warning signs early, such as engine noise, loss of power, or unexpected fuel consumption.
Is It Safe to Drive with Code P3425?
While your vehicle may still be drivable with code P3425 present, it is not recommended to ignore it. An open circuit in the intake valve control can:
- Cause your engine to run inefficiently
- Lead to increased emissions and reduced fuel economy
- Result in engine misfires or internal damage over time
- Promptly diagnosing and repairing the issue can prevent further damage and restore full performance.
Conclusion
DTC P3425 – Cylinder 4 Deactivation/Intake Valve Control Circuit/Open is an indicator of an electrical malfunction in the cylinder deactivation system, specifically related to the intake valve control circuit for cylinder 4. This open circuit could be caused by a failed solenoid, broken wiring, or even engine oil issues.
By understanding how the system works and following a step-by-step diagnostic approach, you can accurately identify the root cause and apply the appropriate repair.
Whether you’re a technician or a vehicle owner, addressing this issue quickly will help maintain your engine’s performance, efficiency, and longevity.
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