P05D9: PCV Regulator Valve Control Circuit Low

Severity

Medium

System

Vehicle Speed and Idle Control

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 P05D9 Mean?

P05D9 is a diagnostic trouble code indicating: PCV Regulator Valve Control Circuit Low. This code relates to the vehicle speed and idle control system. The vehicle's computer detected a condition outside normal operating parameters and stored this code.

Symptoms of P05D9

⚠️ Check Engine Light (MIL) illuminated
⚠️ PCV Regulator Valve reading at zero or minimum value
⚠️ Related system not functioning or in fail-safe mode
⚠️ Erratic idle speed

Common Causes

🔍 Open or broken wire in PCV Regulator Valve circuit
🔍 Poor ground connection at PCV Regulator Valve
🔍 Faulty PCV Regulator Valve with no output signal
🔍 Disconnected or loose PCV Regulator Valve connector
🔍 Blown fuse in related circuit

Frequently Asked Questions

What does P05D9 mean?

P05D9 indicates: PCV Regulator Valve Control Circuit Low. The vehicle's computer has detected that the PCV Regulator Valve is not operating within its expected parameters and stored this diagnostic trouble code.

Can I drive with code P05D9?

You can drive short distances for essential trips, but schedule a diagnosis soon. Driving with P05D9 for extended periods may cause additional problems.

How much does it cost to fix P05D9?

Repair costs for P05D9 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 PCV Regulator Valve circuit
🔧 Clean and secure PCV Regulator Valve connector and ground points
🔧 Replace failed PCV Regulator Valve

1
Find your vehicle above
Click your make and model for real owner reports and common causes specific to your vehicle.
2
Check for recalls
Go to nhtsa.gov/recalls and enter your VIN. Free repairs if covered.
3
Get a professional diagnosis
A code alone doesn't identify the exact failed part. A diagnostic ($50–$150) pinpoints the root cause.

Related Codes

P0500 Vehicle Speed Sensor A Circuit P0501 Vehicle Speed Sensor A Circuit Range/Performance P0502 Vehicle Speed Sensor A Circuit Low P0503 Vehicle Speed Sensor Circuit Intermittent/High P0504 Brake Switch A/B Correlation P0505 Idle Control System P0506 Idle Control System RPM - Lower Than Expected P0507 Idle Control System RPM - Higher Than Expected P0508 Idle Air Control Circuit Low P0509 Idle Air Control Circuit High