Glow Plug #2 Circuit Failure
The P0672 code indicates a malfunction in the glow plug circuit for cylinder #2. Glow plugs are used in diesel engines to heat the combustion chamber for cold starts. This code is set when the powertrain control module (PCM) detects an abnormal voltage or resistance in the glow plug #2 circuit, often due to a faulty glow plug, open or shorted wiring, or a bad relay. This can cause hard starting, misfiring, and increased emissions, especially in cold weather.
1. Most Common Causes
- Faulty glow plug #2
- Open or shorted wiring in glow plug #2 circuit
- Bad glow plug relay or fuse
- Corroded or loose connector at glow plug #2
- Failed PCM (rare)
2. Symptoms You Will Notice
- Hard starting, especially in cold weather
- Engine misfire or rough idle on cold start
- White smoke from exhaust on startup
- Check Engine Light illuminated
- Reduced fuel economy
3. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Visually inspect glow plug #2 wiring and connector for damage or corrosion.
Step 3: Test glow plug #2 resistance with a multimeter (specs: 0.5-2.0 ohms).
Step 4: Check voltage at glow plug #2 connector during glow cycle (should be battery voltage).
Step 5: Inspect glow plug relay and fuse for proper operation.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
You can drive short distances in mild weather, but avoid cold starts and long trips. The vehicle may be hard to start and could cause additional strain on the battery and starter.
How much does it cost to fix?▼
Typically $50-$150 for a single glow plug replacement, including parts and labor. If wiring or relay issues are found, costs may increase.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.