This post contains affiliate links. This means I will make a commission at no extra cost to you should you click through and make a purchase [ “As an Amazon Associate, I earn from qualifying purchases.” ]. Read the full disclosure here.
P3447 Cylinder 6 Exhaust Valve Control Circuit Low GuideMechanic.Com As engines become more complex and efficient, onboard diagnostic systems are designed to monitor every aspect of engine performance.
One such feature is cylinder deactivation, which reduces fuel consumption and emissions by turning off certain cylinders during light-load driving conditions.
In vehicles equipped with this technology, malfunctioning components can trigger Diagnostic Trouble Codes (DTCs), such as P3447.
This article covers the P3447 trouble code, what it means, its common symptoms and causes, how to diagnose it, and how to fix it effectively.
See Also: P3446 Cylinder 6 Exhaust Valve Control Circuit Performance
P3447 Cylinder 6 Exhaust Valve Control Circuit Low
What is P3447?
DTC Definition: P3447 – Cylinder 6 Exhaust Valve Control Circuit Low
This code indicates that the engine control module (ECM) has detected a low voltage condition in the exhaust valve control circuit for cylinder 6.
This suggests an electrical issue — likely a short to ground, high resistance, or a faulty component — that is affecting the proper operation of the solenoid responsible for controlling the exhaust valve during cylinder deactivation.
Understanding Cylinder Deactivation and Valve Control
In engines equipped with Active Fuel Management (AFM), Displacement on Demand (DoD), or other cylinder deactivation systems, certain cylinders are shut off under light loads to improve fuel economy.
This process involves:
Oil control solenoids that direct pressurized oil to special hydraulic valve lifters.
These lifters collapse when pressurized, preventing the valves from opening, effectively deactivating the cylinder.
Both intake and exhaust valves are involved.
The ECM controls these solenoids and monitors their performance.
In the case of P3447, the circuit responsible for controlling the exhaust valve of cylinder 6 is not receiving the correct voltage level, which interferes with cylinder deactivation and engine performance.
Symptoms of P3447
The vehicle may display various signs when P3447 is present, including:
Illuminated Check Engine Light (CEL)
Reduced fuel efficiency
Rough idling
Engine hesitation under acceleration
Increased tailpipe emissions
Possible engine misfires
Poor or sluggish engine performance
In some vehicles, you might not notice any immediate drivability concerns, but ignoring this code can lead to long-term engine wear and decreased efficiency.
P3447 Cylinder 6 Exhaust Valve Control Circuit Low
Causes of P3447
Several factors can lead to a low voltage condition in the Cylinder 6 exhaust valve control circuit:
1. Faulty Exhaust Valve Control Solenoid
If the solenoid controlling the exhaust valve is damaged or worn out, it may short internally, leading to a low voltage reading.
2. Short to Ground in the Circuit
Damaged wiring or exposed conductors may cause the circuit to short to the engine block or vehicle frame, resulting in low voltage.
3. Corroded or Damaged Connectors
Moisture or dirt buildup in the solenoid connectors can increase resistance or create unintended paths for electrical current.
4. Faulty Valve Lifter Oil Manifold (VLOM)
The VLOM distributes oil pressure to solenoids; internal faults in this manifold can mimic electrical faults or cause low voltage behavior.
5. Malfunctioning ECM or PCM
The engine control module may be at fault if it fails to properly send or interpret voltage signals.
6. Low or Dirty Engine Oil
Oil that is old or contaminated may clog the oil passages or reduce pressure needed to activate the lifters, indirectly affecting electrical signals.
P3447 Cylinder 6 Exhaust Valve Control Circuit Low
How to Diagnose P3447
Proper diagnosis is critical to avoid unnecessary part replacements. Follow these steps:
1. Scan for DTCs
Use a professional OBD-II scan tool to verify the presence of P3447. Look for other related codes (P3445–P3448), which may indicate a larger issue.
2. Visual Inspection
Inspect all visible wiring and connectors associated with the cylinder 6 exhaust valve control solenoid. Look for:
Frayed or burnt wires
Loose or corroded connectors
Oil-soaked cables
3. Test the Solenoid
Unplug the solenoid and measure resistance with a multimeter. Compare the value with manufacturer specifications (typically around 6–10 ohms). A reading near 0 ohms or infinite resistance may indicate a short or open.
4. Check for Short to Ground
With the ignition OFF, check for continuity between the control wire and engine ground. If continuity exists, a short to ground is likely present in the wiring.
5. Verify Power and Ground
With the key ON, use a multimeter or test light to ensure that the solenoid is receiving proper voltage (usually 12V). If not, the circuit may have a break or excessive resistance.
6. ECM Output Test
Using an advanced scan tool, command the solenoid to activate and monitor its response. If the ECM fails to control it properly despite good wiring, the ECM may be at fault.
P3447 Cylinder 6 Exhaust Valve Control Circuit Low
How to Fix Code P3447
Once the root cause has been diagnosed, appropriate repairs should be made. Common fixes include:
1. Replace the Exhaust Valve Control Solenoid
If tests reveal that the solenoid is shorted or not functioning correctly, it should be replaced. Always use OEM or high-quality parts.
2. Repair or Replace Wiring and Connectors
If the circuit is shorted to ground, repair the damaged section of wiring. Clean and secure all connections, and use dielectric grease to prevent future corrosion.
3. Replace or Service the VLOM
If the Valve Lifter Oil Manifold is malfunctioning, it may need replacement. This typically requires removing the intake manifold for access.
4. Perform an Oil Change
Old or dirty oil can interfere with hydraulic functions. Drain and refill with manufacturer-recommended oil and replace the oil filter.
5. Replace or Reflash the ECM
If the ECM is confirmed faulty, it may need to be reprogrammed or replaced — though this is rare and should only be done after all other components have been tested.
P3447 Cylinder 6 Exhaust Valve Control Circuit Low
Is It Safe to Drive with P3447?
Driving with a P3447 code may not cause immediate failure, but it is not advisable in the long term. Potential risks include:
Increased fuel consumption
Higher emissions
Engine misfires
Catalytic converter damage
Worsening drivability problems
Prompt diagnosis and repair will restore engine efficiency and protect other components from wear or damage.
Preventing P3447 in the Future
You can minimize the risk of DTC P3447 by following basic maintenance practices:
Use High-Quality Motor Oil
Stick to manufacturer-recommended oil types and change it at proper intervals.
Inspect Wiring Regularly
During routine service, inspect engine bay wiring for damage or corrosion.
Avoid Excessive Idling and Short Trips
These conditions can promote sludge buildup and reduce oil quality.
Address Check Engine Lights Promptly
Ignoring warning signs can lead to more severe problems and costlier repairs.
Conclusion
DTC P3447 points to a low voltage condition in the exhaust valve control circuit for cylinder 6, which affects the engine’s ability to deactivate the cylinder under certain conditions.
While the car may still run, it won’t perform optimally and may eventually suffer from long-term wear and reduced fuel efficiency.
Accurate diagnosis, starting with a scan and physical inspection, followed by tests on the solenoid, wiring, and ECM, will lead to an effective repair.
Fixing this issue not only restores proper performance but also ensures that your engine operates efficiently and cleanly, as intended by the manufacturer.
- P3455 Cylinder 7 Exhaust Valve Control Circuit Low - June 4, 2025
- P3454 Cylinder 7 Exhaust Valve Control Circuit Performance - June 4, 2025
- Cylinder 7 Exhaust Valve Control Circuit/Open - June 4, 2025