Cylinder 4 Exhaust Valve Control Circuit Low
Diagnostic trouble code P3431 indicates that the powertrain control module (PCM) has detected a low voltage condition in the control circuit for the cylinder 4 exhaust valve deactivation mechanism. This typically means the circuit is shorted to ground or has high resistance, preventing the cylinder deactivation system from operating correctly on cylinder 4.
While not an immediate safety hazard, this code disables the cylinder deactivation system and can cause rough running or reduced fuel economy. It should be diagnosed and repaired soon to prevent potential internal engine wear or catalytic converter stress.
Common symptoms
- Illuminated Check Engine Light
- Engine misfire or rough idle
- Decreased fuel efficiency
- Lack of engine power or hesitation
- Cylinder deactivation system disabled
Likely causes
- Faulty cylinder 4 exhaust valve control solenoid
- Wiring harness damage (short to ground or open circuit) in the control circuit
- Corroded, loose, or damaged electrical connector at the solenoid
- Low engine oil pressure or restricted oil passages
- Mechanical failure within the cylinder 4 valve lifter assembly
- Faulty Powertrain Control Module (PCM) (rare)
What to check before replacing parts
Check engine oil level and condition.
Look for: Low oil level or extremely dirty oil can prevent the hydraulic cylinder deactivation system from functioning properly. Ensure oil is full and clean.
Visually inspect the wiring and connector for the cylinder 4 exhaust valve control solenoid.
Look for: Look for frayed wires, melted insulation, or a loose/corroded connector that could cause a short to ground or open circuit.
Measure the resistance of the cylinder 4 exhaust valve control solenoid using a multimeter.
Look for: Compare the resistance reading to the manufacturer's specification. An out-of-spec reading (often an open or shorted coil) indicates a faulty solenoid.
Test the control circuit for voltage and ground signals from the PCM.
Look for: With the key on, engine off (or using a bidirectional scan tool to command the solenoid), verify that the PCM is sending the correct voltage and ground. Lack of voltage indicates a wiring or PCM issue.
Perform an engine oil pressure test.
Look for: Connect a mechanical oil pressure gauge to verify that the engine is producing sufficient oil pressure according to factory specs, as low pressure can trigger valve control codes.
This page explains the generic P3431 definition and is general reference information, not a diagnosis for your specific vehicle. Actual causes, severity, and repairs vary by make, model, engine, and mileage — always confirm with a scan tool and a qualified technician before replacing parts.
Gear guide: Best OBD2 ScannersRead this code yourself next time — from $20 Bluetooth dongles to bidirectional scan tools.Rather have a pro handle it? Find a vetted local mechanic.