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P3457 Cylinder 8 Deactivation/Intake Valve Control Circuit/Open GuideMechanic.Com Modern automotive engines are equipped with advanced technologies that enhance fuel efficiency and reduce emissions without compromising performance.
One such system is cylinder deactivation, found in many V6 and V8 engines. When something goes wrong in this system, diagnostic trouble codes (DTCs) are stored in the vehicle’s engine control module (ECM) or powertrain control module (PCM). One such DTC is P3457, which relates to cylinder 8 deactivation and its intake valve control circuit.
This article will explain in detail what the P3457 code means, what causes it, what symptoms to look out for, and how to diagnose and fix it properly.
See Also: P3456 Cylinder 7 Exhaust Valve Control Circuit High
P3457 Cylinder 8 Deactivation/Intake Valve Control Circuit/Open
What Does Code P3457 Mean?
The P3457 code is an OBD-II (On-Board Diagnostics II) generic powertrain trouble code that indicates a fault in the intake valve control circuit for cylinder number 8.
Specifically, it means the PCM has detected an open circuit condition, preventing proper activation or deactivation of the intake valve on cylinder 8 during engine operation.
This code usually appears in engines that support cylinder deactivation technology, such as General Motors’ Active Fuel Management (AFM) or Honda’s Variable Cylinder Management (VCM). These systems deactivate some cylinders under light load to save fuel and reduce emissions.
In this context, an “open” circuit refers to a disruption or break in the electrical pathway that controls the intake valve’s actuator or solenoid for cylinder 8, leading to improper operation of the deactivation mechanism.
Cylinder Deactivation: A Quick Overview
In V6 and V8 engines, cylinder deactivation works by shutting down specific cylinders under light engine load conditions (like cruising or idling). This is done by:
- Disabling fuel injection
- Locking valve lifters or deactivating solenoids, keeping valves closed
- Preventing intake and exhaust valves from opening
- The system is controlled electronically by the PCM, which engages or disengages cylinder operation based on load, throttle input, RPM, and oil pressure.
- When this system fails for cylinder 8—specifically the intake valve control mechanism—code P3457 is triggered.
P3457 Cylinder 8 Deactivation/Intake Valve Control Circuit/Open
Causes of the P3457 Code
Several mechanical and electrical issues can lead to the P3457 Cylinder 8 Deactivation/Intake Valve Control Circuit/Open code. Here are the most common causes:
Faulty Intake Valve Solenoid (Cylinder 8)
The most direct cause is a malfunctioning solenoid that fails to activate or deactivate properly.
Open or Shorted Wiring
A break or short in the wiring to the cylinder 8 intake valve control solenoid will prevent proper signal transmission.
Loose or Corroded Electrical Connectors
Faulty or dirty connectors can disrupt electrical flow, causing the PCM to detect an open circuit.
Oil Pressure Issues
Many deactivation systems use engine oil pressure to control lifters and solenoids. Low oil pressure or dirty oil can impair functionality.
Faulty PCM or ECM
Although rare, a malfunctioning PCM may fail to deliver the necessary control signals.
Worn or Stuck Valve Lifter
A mechanical failure in the lifter mechanism may mimic the electrical symptoms of a circuit issue.
P3457 Cylinder 8 Deactivation/Intake Valve Control Circuit/Open
Common Symptoms of P3457
When code P3457 is active, the engine may behave abnormally. Here are the most common symptoms:
Check Engine Light (CEL) is on
The most immediate and obvious sign is the illuminated CEL on the dashboard.
Poor Fuel Economy
The cylinder deactivation system helps improve MPG. If it fails, fuel efficiency drops.
Rough Engine Idle
Cylinder 8 not activating properly can cause an uneven idle.
Engine Misfires or Vibrations
If the intake valve doesn’t open correctly, the cylinder can misfire or vibrate.
Reduced Engine Performance
You may notice sluggish acceleration or poor throttle response.
Ticking or Clicking Noise from Engine
Mechanical issues like a stuck lifter may cause audible noise.
P3457 Cylinder 8 Deactivation/Intake Valve Control Circuit/Open
How to Diagnose P3457
Proper diagnosis of code P3457 requires a mix of electronic and mechanical inspection. Here’s a step-by-step guide:
1. Scan for Codes
Use a professional-grade OBD-II scanner to confirm the presence of P3457. Check for other codes in the P3400-P3499 range, which often relate to cylinder deactivation.
2. Visual Inspection
Inspect all wiring and connectors associated with the cylinder 8 intake valve control solenoid.
Look for damaged insulation, broken wires, or exposed conductors.
Check for loose, dirty, or corroded connectors.
3. Test the Solenoid
Disconnect the cylinder 8 intake valve control solenoid and test its resistance with a multimeter.
Compare readings to the manufacturer’s specs.
A solenoid with infinite resistance or no continuity is likely faulty.
4. Check Oil Level and Condition
Inspect the engine oil level and look for signs of contamination or sludge.
Dirty or degraded oil can impair the function of hydraulic components in the valve control system.
5. Inspect Valve Lifter Operation (if accessible)
A physical inspection of the lifter (if possible) can help rule out mechanical failure.
6. Test PCM Signals
If all else checks out, the issue might lie in the PCM or its output circuit. Use an oscilloscope or advanced scan tool to test signal strength and continuity from the PCM to the solenoid.
P3457 Cylinder 8 Deactivation/Intake Valve Control Circuit/Open
Common Repairs for P3457
Once the problem is diagnosed, you can apply the appropriate fix. Here are some common solutions:
Replace Cylinder 8 Intake Valve Control Solenoid
If faulty, replacing the solenoid will restore circuit functionality.
Repair or Replace Damaged Wiring/Connectors
If a wire is open or shorted, repair it or replace the section as needed.
Clean or Replace Corroded Electrical Connectors
Ensure solid connections for proper signal delivery.
Change Engine Oil and Filter
If the oil is old or contaminated, perform an oil change with the recommended viscosity.
Replace the PCM (if necessary)
In rare cases, the control module may be at fault. Reprogramming or replacement may be required.
Preventing P3457 in the Future
To avoid recurrence of the P3457 trouble code, consider these maintenance tips:
Perform Regular Oil Changes
Use manufacturer-recommended oil types and change at proper intervals.
Inspect Wiring During Routine Service
Look for signs of wear, corrosion, or damage near the engine and harness connections.
Use OEM Parts
For solenoids, sensors, and PCM components, always opt for high-quality, original equipment.
Avoid Aftermarket Tuners or Mods
Unapproved engine modifications can disrupt PCM signals and trigger fault codes.
Conclusion
The P3457 – Cylinder 8 Deactivation/Intake Valve Control Circuit/Open code indicates a failure in a key fuel-saving system in modern engines.
Though it may not immediately cripple the vehicle, ignoring it can lead to reduced fuel economy, rough running, misfires, and long-term engine wear.
Proper diagnosis often reveals an issue with a faulty solenoid, broken wire, or low oil pressure. Fortunately, many of the causes are straightforward to repair, especially if identified early. With regular maintenance and prompt attention to warning signs, you can keep your vehicle running smoothly and efficiently.
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