Cylinder 8 Deactivation/Intake Valve Control Circuit Low
The P3459 code indicates that the powertrain control module (PCM) has detected a low voltage condition in the cylinder 8 deactivation/intake valve control circuit. This circuit is responsible for controlling the oil flow to the cylinder deactivation solenoids, which disable the intake valves to improve fuel economy under light load. A low voltage reading suggests a short to ground, open circuit, or faulty component in the solenoid or wiring.
01. Most Common Causes
- Faulty cylinder 8 deactivation solenoid
- Short to ground in the control circuit wiring
- Open circuit in the wiring or connector
- Corroded or damaged connector pins
- Failed PCM (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced fuel economy
- Engine misfire or rough idle
- Loss of power or hesitation
- Cylinder deactivation system inoperative
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and record freeze frame data.
Step 2: Visually inspect the wiring and connector at cylinder 8 deactivation solenoid for damage, corrosion, or loose connections.
Step 3: Use a multimeter to check the solenoid resistance (typically 10-30 ohms). Replace if out of spec.
Step 4: Check for voltage at the solenoid connector with the engine running (should be battery voltage). If low, test the circuit for shorts or opens.
Step 5: If wiring and solenoid are good, test the PCM output by backprobing the circuit. Replace PCM if no output.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances with this code, as it can cause reduced fuel economy, engine misfire, and potential damage to the catalytic converter. Have it diagnosed promptly.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for diagnosis and repair, depending on whether the solenoid or wiring needs replacement. Parts are usually $20-$80, and labor is about $50-$100.