P3491: Cylinder 12 Deactivation/Intake Valve Control Circuit Low

Severity

Medium

System

Powertrain

Last reviewed: Jan 1, 0001 Last updated: Jan 1, 0001

Methodology: We combine code standards with complaint and reliability patterns, then review for clear, vehicle-first diagnosis steps.

Sources: SAE/OBD-II definitions, manufacturer service information, and public reliability reports (including NHTSA where applicable).

Limits: Guidance is informational and may not match every model-year or revision. Confirm with the official manual and diagnostics before replacing parts. For safety-critical or electrical work, use a qualified technician.

What Does P3491 Mean?

P3491 is a diagnostic trouble code indicating: Cylinder 12 Deactivation/Intake Valve Control Circuit Low. This code relates to the powertrain system. The vehicle's computer detected a condition outside normal operating parameters and stored this code.

Symptoms of P3491

⚠️ Check Engine Light (MIL) illuminated
⚠️ Cylinder 12 Deactivation/Intake Valve reading at zero or minimum value
⚠️ Related system not functioning or in fail-safe mode
⚠️ Reduced engine performance

Common Causes

🔍 Open or broken wire in Cylinder 12 Deactivation/Intake Valve circuit
🔍 Poor ground connection at Cylinder 12 Deactivation/Intake Valve
🔍 Faulty Cylinder 12 Deactivation/Intake Valve with no output signal
🔍 Disconnected or loose Cylinder 12 Deactivation/Intake Valve connector
🔍 Blown fuse in related circuit

Frequently Asked Questions

What does P3491 mean?

P3491 indicates: Cylinder 12 Deactivation/Intake Valve Control Circuit Low. The vehicle's computer has detected that the Cylinder 12 Deactivation/Intake Valve is not operating within its expected parameters and stored this diagnostic trouble code.

Can I drive with code P3491?

You can drive short distances for essential trips, but schedule a diagnosis soon. Driving with P3491 for extended periods may cause additional problems.

How much does it cost to fix P3491?

Repair costs for P3491 typically range from $20 to $300, depending on the root cause. Simple wiring or connector repairs are on the lower end, while component replacement costs more. A proper diagnosis ($80–$150 at most shops) will identify the exact cause before committing to expensive parts.

What To Do Next

Possible Fixes

🔧 Repair broken wire or restore ground in Cylinder 12 Deactivation/Intake Valve circuit
🔧 Clean and secure Cylinder 12 Deactivation/Intake Valve connector and ground points
🔧 Replace failed Cylinder 12 Deactivation/Intake Valve

1
Find your vehicle above
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2
Check for recalls
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3
Get a professional diagnosis
A code alone doesn't identify the exact failed part. A diagnostic ($50–$150) pinpoints the root cause.