Glow Plug Control Module Circuit Low
The P0383 code indicates that the powertrain control module (PCM) has detected a low voltage condition in the glow plug control module circuit. This circuit is responsible for controlling the glow plugs during cold starts in diesel engines. A low voltage reading suggests a short to ground, open circuit, or faulty component, which can prevent proper glow plug operation and cause hard starting in cold weather.
1. Most Common Causes
- No defined failure causes in the published SAE J2012 standard
- Outdated diagnostic software that cannot interpret reserved codes
- Proprietary manufacturer use not publicly documented
- Scanner communication error with the control module
2. Symptoms You Will Notice
- Hard starting, especially in cold weather
- Check Engine Light illuminated
- Excessive white smoke from exhaust on startup
- Rough idle or misfire until engine warms up
3. Step-by-Step Diagnosis
Step 1: Scan for additional codes and check freeze frame data.
Step 2: Visually inspect glow plug control module wiring and connectors for damage or corrosion.
Step 3: Test the control circuit voltage using a multimeter; compare to manufacturer specifications.
Step 4: Check fuses and relays related to the glow plug system.
Step 5: If circuit tests OK, replace the glow plug control module.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with this code, especially in cold weather, as it can cause hard starting and potential stalling. Continued driving may also damage the glow plugs or battery.
How much does it cost to fix?▼
The cost to fix P0383 typically ranges from $50 to $150 for parts and labor, depending on whether the issue is a simple wiring repair or requires replacing the glow plug control module.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.