Turbo/Supercharger Boost Control Circuit Low
The P004C code indicates that the Powertrain Control Module (PCM) has detected a low voltage condition in the turbocharger or supercharger boost control circuit. This circuit typically includes the boost control solenoid, wastegate actuator, or variable geometry turbo actuator. A low voltage reading suggests a short to ground, open circuit, or faulty component, which can prevent proper boost regulation and lead to reduced engine performance.
01. Most Common Causes
- Faulty boost control solenoid
- Open or shorted wiring in boost control circuit
- Corroded or loose electrical connector
- Failed PCM (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine power or acceleration
- Turbocharger not boosting properly
- Possible limp mode activation
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and freeze frame data.
Step 2: Visually inspect boost control solenoid and wiring for damage or corrosion.
Step 3: Test boost control solenoid resistance and operation with a multimeter.
Step 4: Check for 12V power and ground at solenoid connector with key on.
Step 5: If wiring and solenoid are good, test PCM output signal.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as reduced boost can cause poor performance and potential damage to the turbo system. Limp mode may also activate.
How much does it cost to fix?▼
Repair costs typically range from $150 to $400, depending on the faulty component and labor rates. A boost control solenoid replacement is usually $100-$250.