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P3471 Cylinder 9 Exhaust Valve Control Circuit Low GuideMechanic.Com Modern vehicles are equipped with increasingly advanced engine management systems to optimize fuel efficiency, reduce emissions, and improve performance.
Among these systems is cylinder deactivation, which temporarily disables select cylinders during low-load conditions. This technology relies on precise control of intake and exhaust valve mechanisms.
When the system detects a fault, it stores a Diagnostic Trouble Code (DTC). One such code is P3471, which indicates a low voltage condition in the exhaust valve control circuit for cylinder 9. This type of fault suggests an electrical issue affecting how the ECM or PCM controls the valve lifter or solenoid.
This article will break down everything you need to know about DTC P3471, from what it means and how it affects your engine to how to diagnose and fix the issue.
See Also: P3470 Cylinder 9 Exhaust Valve Control Circuit Performance
P3471 Cylinder 9 Exhaust Valve Control Circuit Low
What Is DTC P3471?
Code Definition: P3471 – Cylinder 9 Exhaust Valve Control Circuit Low
This code is triggered when the Engine Control Module (ECM) or Powertrain Control Module (PCM) detects an abnormally low voltage in the control circuit that operates the exhaust valve for cylinder 9.
In engines with cylinder deactivation technology—also known as Displacement on Demand (DoD) or Active Fuel Management (AFM) in General Motors vehicles—special solenoids and valve lifters are used to deactivate specific cylinders by disabling the intake and exhaust valves.
When the ECM tries to activate or deactivate the exhaust valve on cylinder 9, but it detects that the control circuit voltage is too low (below a specified threshold), it logs P3471.
How the Exhaust Valve Control Circuit Works
In vehicles equipped with AFM or DoD:
- The ECM sends a signal to a solenoid, which directs oil pressure to specially designed hydraulic lifters.
- These lifters collapse to prevent the exhaust valve from opening, effectively deactivating the cylinder.
- Once reactivation is needed, oil pressure is removed, and the lifter resumes normal operation.
The exhaust valve control circuit includes:
- Power supply (usually via a relay and fuse)
- Ground connection
- ECM-controlled activation wiring
- Sensors that provide feedback to the ECM
When this circuit experiences low voltage, the solenoid may not operate correctly, preventing the proper functioning of cylinder 9.
P3471 Cylinder 9 Exhaust Valve Control Circuit Low
Affected Vehicles
DTC P3471 is commonly found in General Motors (GM) vehicles using V8 engines with AFM/DoD technology. These include:
- Chevrolet Silverado, Suburban, Tahoe, Camaro
- GMC Sierra, Yukon, Denali
- Cadillac Escalade
- Other GM platforms using 5.3L, 6.0L, or 6.2L V8 engines
Other manufacturers using similar cylinder deactivation strategies may have corresponding codes.
Symptoms of P3471
The presence of code P3471 may result in noticeable or subtle symptoms, depending on how the ECM handles the fault. Common symptoms include:
Illuminated Check Engine Light (CEL)
Rough Idle or Engine Misfire
Especially if the exhaust valve is stuck open or closed.
Decreased Fuel Efficiency
Cylinder deactivation may be disabled, causing more fuel use.
Reduced Power
Engine may run less efficiently if one cylinder isn’t functioning properly.
Engine Ticking Noise
A faulty solenoid or lifter may create a noticeable ticking sound.
Poor Emissions Performance
Incomplete combustion can increase emissions output.
P3471 Cylinder 9 Exhaust Valve Control Circuit Low
Causes of P3471
DTC P3471 typically points to an electrical fault, and several root causes can contribute to this issue:
1. Faulty Exhaust Valve Control Solenoid (Cylinder 9)
The solenoid may be internally shorted or malfunctioning, causing low circuit voltage.
2. Wiring Problems
Damaged, corroded, or shorted wires in the control circuit can result in voltage drops.
3. Poor Ground Connection
A weak or missing ground can reduce voltage in the circuit, preventing proper solenoid operation.
4. Faulty ECM Driver
The ECM may not be sending proper voltage to the control circuit due to an internal fault.
5. Oil Pressure Problems
Although not directly electrical, low or dirty oil can affect solenoid operation, which may trick the ECM into thinking there’s an electrical fault.
6. Connector Issues
Loose, dirty, or corroded connectors can increase resistance and lower voltage in the circuit.
P3471 Cylinder 9 Exhaust Valve Control Circuit Low
Diagnosing P3471
Accurate diagnosis involves testing both the electrical and mechanical components of the exhaust valve control system. Here’s a step-by-step approach:
1. Scan for Additional Codes
Use a diagnostic scan tool to check for related codes such as:
P3469 (Circuit/Open)
P3470 (Circuit Performance)
P3472 (Circuit High)
These can help determine if the problem is isolated or part of a broader issue.
2. Visual Inspection
Inspect the wiring and connectors associated with the cylinder 9 exhaust valve control solenoid. Look for:
Burnt or melted insulation
Pinched wires
Corroded terminals
Oil contamination
3. Test Solenoid Resistance
Disconnect the solenoid connector.
Use a digital multimeter to measure resistance across the terminals.
Normal resistance is typically between 5–15 ohms.
A reading near 0 (short circuit) or infinite (open circuit) indicates a fault.
4. Check for Voltage and Ground
With the ignition on, test the power supply and ground at the connector.
Ensure voltage is within manufacturer specifications (usually 12V).
Any drop may suggest a wiring or grounding issue.
5. Use a Bi-directional Scan Tool
If available, command the solenoid on and off using a scan tool and observe real-time data to see if the system responds correctly.
6. Inspect Oil Level and Quality
Dirty or low oil can cause improper lifter or solenoid performance, which may lead the ECM to interpret a low voltage fault.
P3471 Cylinder 9 Exhaust Valve Control Circuit Low
Repairing DTC P3471
Once the cause is identified, repairs may include:
1. Replacing the Exhaust Valve Control Solenoid
If testing confirms that the solenoid is faulty, replace it with an OEM-quality part.
2. Repairing or Replacing Wiring
Fix any damaged or shorted wires in the control circuit. Use proper insulation and connectors for long-term durability.
3. Cleaning or Replacing Connectors
Use contact cleaner to remove corrosion and improve electrical contact. Replace damaged connectors as needed.
4. Correcting Ground Issues
Ensure the solenoid and ECM ground points are secure, clean, and rust-free.
5. Changing the Oil and Filter
Use the correct oil viscosity and change it if it’s old or contaminated. This supports proper solenoid and lifter function.
6. ECM Testing or Replacement
If the ECM is not supplying correct voltage or ground, it may require reprogramming or replacement—though this is rare.
P3471 Cylinder 9 Exhaust Valve Control Circuit Low
Preventing Code P3471
Preventive measures can help you avoid electrical faults in the exhaust valve control circuit:
- Regular Oil Changes: Use manufacturer-recommended oil and change it at proper intervals.
- Inspect Wiring During Maintenance: Especially on high-mileage vehicles.
- Avoid Aftermarket Electrical Modifications: These can interfere with ECM-controlled circuits.
- Respond Quickly to Early Symptoms: Address engine performance issues or warning lights promptly.
Conclusion
DTC P3471 – Cylinder 9 Exhaust Valve Control Circuit Low is a fault indicating insufficient voltage in the electrical circuit controlling the exhaust valve on cylinder 9.
This can prevent the cylinder deactivation system from functioning properly, reducing performance, increasing fuel consumption, and potentially causing long-term engine issues if left unresolved.
The most common causes include a faulty solenoid, wiring damage, or poor ground connection. Diagnosing the issue involves visual inspections, voltage testing, and resistance measurements. Once identified, most repairs can be made with standard tools and OEM parts.
By staying proactive with oil changes, electrical inspections, and timely diagnostics, you can keep your engine running smoothly and prevent DTCs like P3471 from affecting your vehicle.
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