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P3426 Cylinder 4 Deactivation/Intake Valve Control Circuit Performance GuideMechanic.Com Automotive engines today are more complex and efficient than ever before, thanks in part to advanced systems that manage fuel economy and emissions.
One such innovation is cylinder deactivation, also known as Active Fuel Management (AFM), Displacement on Demand (DoD), or Variable Valve Timing (VVT). This system allows certain cylinders to be temporarily deactivated under light load conditions, helping reduce fuel consumption.
However, as with any complex system, things can go wrong. When a malfunction occurs in the intake valve control circuit of the cylinder deactivation system, your vehicle’s Engine Control Module (ECM) may trigger Diagnostic Trouble Code (DTC) P3426 – Cylinder 4 Deactivation/Intake Valve Control Circuit Performance. In this article, we’ll explore what this code means, what causes it, how to diagnose it, and how to fix it.
See Also: P3427 Cylinder 4 Deactivation/Intake Valve Control Circuit Low
P3426 Cylinder 4 Deactivation/Intake Valve Control Circuit Performance
What Does Code P3426 Mean?
The P3426 trouble code indicates that the ECM has detected a performance issue in the intake valve control circuit for cylinder 4.
Specifically, it means that the intake valve actuator responsible for enabling or disabling the operation of cylinder 4 during deactivation is not performing within the expected range. This is different from a circuit that is open or shorted; in this case, the circuit is functioning but not as it should.
Essentially, the ECM commanded a specific response from the actuator, such as opening or closing the valve, but the response time, voltage, or behavior did not match expected parameters.
How Cylinder Deactivation Works
In cylinder deactivation systems, the intake and exhaust valves of certain cylinders are temporarily disabled during low-load driving conditions.
This is achieved through a series of oil control solenoids and hydraulic lifters that collapse and hold the valves in the closed position.
The ECM controls these solenoids electronically, commanding them to activate or deactivate based on engine speed, load, throttle position, and other factors.
When a deactivation event is initiated, oil pressure is rerouted to the valve lifters, causing them to collapse and stop the valve motion.
If the solenoid that controls the intake valve on cylinder 4 doesn’t perform correctly, the ECM detects the anomaly and sets the P3426 code.
P3426 Cylinder 4 Deactivation/Intake Valve Control Circuit Performance
Symptoms of P3426
If your vehicle sets a P3426 code, you may notice one or more of the following symptoms:
- Illuminated Check Engine Light (CEL)
- Rough engine idle
- Poor acceleration or reduced power
- Increased fuel consumption
- Abnormal engine noise, such as ticking or knocking
- Engine misfire, particularly on cylinder 4
- Unstable RPM at idle
In some cases, there may be no immediate drivability symptoms other than the CEL. However, leaving the issue unresolved can cause long-term engine damage or inefficiency.
Common Causes of P3426
Several conditions can cause code P3426 to be set. The most common include:
Faulty Cylinder 4 Intake Valve Control Solenoid
If the solenoid becomes stuck, slow, or weak in operation, the ECM may detect performance outside expected parameters.
Oil Pressure Issues
Dirty, low, or incorrect engine oil can prevent the solenoid from activating the lifter properly.
Clogged Oil Passages
Carbon buildup or sludge can block the oil channels needed for proper lifter operation.
Electrical Problems
Wiring issues such as corrosion, damaged connectors, or loose pins in the intake valve solenoid harness can interfere with signal accuracy.
PCM/ECM Software Malfunction or Failure
In rare cases, the vehicle’s computer may misread inputs or send incorrect commands.
Hydraulic Lifter Failure
If the lifter cannot collapse or expand as commanded, it will prevent the valve from functioning properly.
Diagnosing Code P3426
Accurate diagnosis of P3426 involves both electrical and mechanical evaluation. Below is a step-by-step guide:
1. Verify the Code
Use a professional OBD-II scanner to confirm the presence of code P3426.
Check for any related codes like P3400-P3497 which may indicate other cylinder deactivation faults.
2. Inspect Engine Oil
Check oil level, condition, and viscosity.
Dirty or low oil can lead to improper valve operation due to reduced hydraulic pressure.
3. Visual Inspection
Inspect the wiring harness and connectors leading to the cylinder 4 intake valve solenoid.
Look for frayed wires, corrosion, broken insulation, or loose connections.
4. Test the Solenoid
Disconnect the intake valve control solenoid and use a multimeter to test resistance.
Typical solenoids should show a resistance of around 10–20 ohms. Out-of-range values suggest a malfunction.
5. Check for Proper Signal
Use a scan tool or oscilloscope to monitor the command signals and feedback from the solenoid while the engine is running.
Compare response times and voltages against manufacturer specifications.
6. Inspect Oil Control Passages
Remove the solenoid and inspect for debris or sludge in the oil ports.
Clean or flush as necessary.
How to Fix Code P3426
Depending on the root cause, one or more of the following repairs may be required:
Replace Cylinder 4 Intake Valve Control Solenoid
If solenoid resistance is outside specs or if internal failure is detected.
Change Engine Oil and Filter
Always use manufacturer-recommended oil viscosity to ensure proper hydraulic operation.
Clean or Replace Electrical Connectors
Remove corrosion and secure any loose connections.
Repair or Replace Damaged Wiring
Restore signal integrity by fixing any damaged circuits.
Flush or Clean Oil Passages
This helps restore proper oil flow to the solenoids and lifters.
Replace Hydraulic Lifters (if required)
Only if it’s confirmed they are sticking or not collapsing correctly.
Reprogram or Replace PCM/ECM
Only as a last resort when all other possibilities have been ruled out.
Once repairs are complete, clear the code with a scanner and perform a test drive to confirm the issue is resolved.
Is It Safe to Drive with a P3426 Code?
Technically, the vehicle may still be operable with a P3426 code. However, continued driving could:
Result in permanent damage to valvetrain components
Cause poor fuel economy
Lead to engine misfires
Increase emissions, potentially failing smog checks
Trigger limp mode if the fault persists
Therefore, it is strongly recommended to address the issue promptly to avoid further complications.
Preventing P3426
Like many engine performance issues, the best way to prevent P3426 is regular maintenance:
Follow scheduled oil changes, using high-quality oil with the correct viscosity.
Avoid extended oil change intervals, especially under heavy-duty conditions.
Inspect wiring during routine maintenance, especially around solenoids and connectors.
Monitor engine performance and address any early warning signs like rough idling or unusual noises.
By keeping your engine clean and well-lubricated, you can greatly reduce the chances of cylinder deactivation issues.
Conclusion
DTC P3426 – Cylinder 4 Deactivation/Intake Valve Control Circuit Performance points to a performance-related issue in the intake valve control circuit of cylinder 4 in engines equipped with cylinder deactivation systems. While not always catastrophic, ignoring the problem can lead to larger engine issues and decreased performance.
With proper diagnosis—starting from oil inspection to electrical testing—you can identify the root cause and apply the right fix. Maintaining clean oil and functional electrical components is the key to avoiding this and other similar trouble codes.
Stay on top of your maintenance schedule, and don’t hesitate to consult a certified technician if you’re unsure about a diagnosis or repair.
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