Coolant Degassing Valve Control Circuit Low
The P2679 code indicates that the powertrain control module (PCM) has detected a low voltage condition in the control circuit of the coolant degassing valve. This valve is responsible for releasing air from the cooling system to prevent vapor lock and ensure proper coolant flow. A low circuit voltage typically points to a short to ground, open circuit, or a faulty valve solenoid. This can lead to cooling system inefficiency and potential engine overheating.
1. Most Common Causes
- Faulty coolant degassing valve solenoid
- Short to ground in the control circuit wiring
- Open circuit or poor connection in the valve harness
- Failed PCM (rare)
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Engine overheating or higher than normal operating temperature
- Coolant loss or visible leaks near the degassing valve
- Poor heater performance
3. Step-by-Step Diagnosis
Step 1: Scan for additional codes and record freeze frame data.
Step 2: Visually inspect the coolant degassing valve and its connector for damage, corrosion, or loose pins.
Step 3: Using a multimeter, check the valve's resistance (typically 10-30 ohms). Replace if out of spec.
Step 4: Test the control circuit for voltage and ground integrity. Repair any shorts or opens found.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended. The low circuit condition may prevent the degassing valve from operating, leading to air trapped in the cooling system, which can cause engine overheating and serious damage.
How much does it cost to fix?▼
The repair cost typically ranges from $50 to $150, including parts (valve solenoid) and labor. Diagnostic fees may add $50-$100.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.