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P3437 Cylinder 5 Exhaust Valve Control Circuit/Open GuideMechanic.Com Modern engines are marvels of engineering, combining mechanical precision with sophisticated electronics to optimize performance, efficiency, and emissions.
One critical part of this advanced system is the variable valve control and cylinder deactivation system, which allows engines to deactivate specific cylinders during light-load conditions to save fuel.
When a malfunction is detected in these systems, the Engine Control Module (ECM) triggers a Diagnostic Trouble Code (DTC). One such code is P3437, which refers to a fault in the Cylinder 5 Exhaust Valve Control Circuit.
This article explores the P3437 trouble code in detail, including what it means, how it affects your vehicle, common causes, diagnostic steps, and repair options.
See Also: P3436 Cylinder 5 Deactivation/Intake Valve Control Circuit High
P3437 Cylinder 5 Exhaust Valve Control Circuit/Open
What Does P3437 Mean?
The P3437 code is defined as “Cylinder 5 Exhaust Valve Control Circuit/Open.” This code appears when the Powertrain Control Module (PCM) or Engine Control Module (ECM) detects an open circuit or no continuity in the exhaust valve control circuit for cylinder number 5.
This issue is usually found in vehicles equipped with Active Fuel Management (AFM), Displacement on Demand (DoD), or similar cylinder deactivation technologies.
These systems deactivate cylinders during certain driving conditions to improve fuel economy. In these systems, oil pressure-actuated solenoids and specially designed lifters are used to disable or enable the valves for specific cylinders.
If the ECM senses that the exhaust valve for cylinder 5 cannot be controlled—due to an open circuit or electrical failure—it will set the P3437 code and typically illuminate the Check Engine Light.
How the Cylinder Deactivation System Works
To better understand this code, it helps to briefly review how the cylinder deactivation system functions:
- The ECM sends an electrical signal to solenoids located in the Valve Lifter Oil Manifold (VLOM).
- These solenoids redirect pressurized engine oil to specialized lifters on the intake and exhaust valves of selected cylinders (like cylinder 5).
- This hydraulic pressure collapses the lifter, preventing it from opening the valve—effectively deactivating the cylinder.
- When full engine power is required, the ECM reactivates the solenoid, restoring normal valve operation.
- If there’s an open circuit in the wiring or solenoid for the exhaust valve of cylinder 5, the ECM cannot command the valve properly, leading to code P3437.
P3437 Cylinder 5 Exhaust Valve Control Circuit/Open
Symptoms of P3437
When the P3437 code is triggered, you may notice several symptoms, depending on the severity of the fault and your vehicle’s system. These symptoms include:
- Check Engine Light On: The most common and immediate symptom.
- Engine Misfire or Rough Idle: Cylinder 5 may not function correctly, leading to rough idling or misfires.
- Reduced Engine Power: You may feel a loss of acceleration or overall engine performance.
- Decreased Fuel Economy: If cylinder deactivation fails, the engine may consume more fuel than usual.
- Ticking or Tapping Noises: A malfunctioning lifter or solenoid can produce unusual sounds.
In some cases, there may be no noticeable symptoms other than the Check Engine Light, especially if the system fails in a “default” or safe state.
Common Causes of Code P3437
There are several possible reasons why the ECM may trigger the P3437 code. These include:
- Open or Broken Wiring in the Exhaust Valve Control Circuit: Damaged wires can interrupt the electrical signal from the ECM to the solenoid.
- Faulty Exhaust Valve Control Solenoid: The solenoid may have failed internally, creating an open circuit.
- Corroded or Loose Electrical Connectors: Connectors exposed to moisture, dirt, or heat can corrode or become loose.
- Valve Lifter Oil Manifold (VLOM) Issues: Malfunctioning components within the VLOM can affect solenoid operation.
- Engine Oil Issues: Low oil levels, dirty oil, or the wrong oil viscosity can cause the system to operate improperly.
- Faulty Valve Lifter: A mechanical failure in the lifter may cause the exhaust valve to remain open or closed incorrectly.
- Defective ECM or Software Glitch: In rare cases, the ECM may misinterpret signals due to internal faults or outdated programming.
P3437 Cylinder 5 Exhaust Valve Control Circuit/Open
Diagnosing P3437
Accurate diagnosis of the P3437 code requires a methodical approach. Here are the steps typically taken by technicians:
1. Scan for Codes
Use an OBD-II scanner to confirm P3437 and check for related codes (e.g., P3400–P3497), which may provide additional clues.
2. Visual Inspection
Inspect the wiring and connectors around the cylinder 5 solenoid. Look for:
Frayed wires
Corrosion
Disconnected or loose plugs
3. Check Engine Oil
Verify that the engine oil is clean, full, and the correct viscosity. Oil pressure plays a key role in solenoid and lifter function.
4. Test the Solenoid
Use a digital multimeter to measure resistance across the solenoid terminals. An open circuit or infinite resistance indicates a fault.
5. Continuity Test
Check for continuity in the circuit wiring between the ECM and the solenoid.
6. Command Test
Using a scan tool with bidirectional control, attempt to activate the solenoid and monitor its response.
7. Check ECM Function
If all components check out but the code persists, consider testing or reprogramming the ECM.
Repairing Code P3437
The necessary repair will depend on the specific cause identified during diagnostics. Common fixes include:
- Repair or Replace Damaged Wiring: Fix broken, shorted, or open wires in the control circuit.
- Replace the Cylinder 5 Exhaust Valve Solenoid: If the solenoid is defective, replacing it can resolve the issue.
- Clean or Replace Electrical Connectors: Corroded or loose connectors should be cleaned, tightened, or replaced.
- Replace the Valve Lifter Oil Manifold (VLOM): If the manifold is clogged or faulty, replacement may be necessary.
- Perform an Oil Change: Use fresh oil with the correct viscosity to ensure proper pressure and operation.
- Replace Faulty Lifters: A damaged or stuck lifter will need to be replaced.
Reprogram or Replace ECM: In rare cases, the engine control module may require reprogramming or replacement.
P3437 Cylinder 5 Exhaust Valve Control Circuit/Open
Can You Drive With Code P3437?
While it may be possible to drive short distances with code P3437, it is not recommended for the following reasons:
- Engine performance and fuel efficiency may suffer.
- Unburned fuel due to misfires can damage the catalytic converter.
- Long-term operation can cause further mechanical damage.
- It is best to address the issue promptly to prevent expensive engine damage and ensure your vehicle runs smoothly.
Preventing Future Occurrences
You can reduce the risk of encountering code P3437 again by following these maintenance tips:
- Use the Right Oil: Stick to manufacturer-recommended oil grades and change it regularly.
- Check for Leaks: Keep an eye on oil levels and top up when necessary.
- Address Check Engine Lights Quickly: Don’t ignore warning lights or delay repairs.
- Inspect Wiring During Regular Maintenance: Especially in older or high-mileage vehicles.
Conclusion
The P3437 Cylinder 5 Exhaust Valve Control Circuit/Open code is a specific fault that indicates an open or broken electrical circuit related to the exhaust valve control of cylinder number 5.
This fault disrupts proper valve operation, which can degrade engine performance, increase fuel consumption, and potentially lead to more serious damage if not addressed.
With a proper understanding of the code, its causes, symptoms, and fixes, vehicle owners and technicians can take the right steps to diagnose and resolve the issue quickly and effectively.
As with most engine-related problems, timely diagnosis and maintenance are crucial to keeping your engine healthy and running at its best.
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