Glow Plug #2 Circuit Failure
The P0672 code indicates a malfunction in the glow plug #2 circuit, which is responsible for heating the combustion chamber in diesel engines for cold starts. The Powertrain Control Module (PCM) detects an open or short circuit in the glow plug or its wiring, preventing proper cylinder heating. This can lead to hard starting, misfires, and increased emissions, especially in cold weather.
01. Most Common Causes
- Faulty glow plug #2
- Open or short in glow plug wiring or connector
- Failed glow plug relay or fuse
- PCM or engine control module issue
02. Symptoms You Will Notice
- Hard starting, especially in cold weather
- Engine misfire or rough idle on startup
- Check Engine Light illuminated
- Excessive white smoke from exhaust on cold start
03. 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 glow plug relay and fuse for proper operation.
Step 5: If wiring and plug are good, test PCM output to glow plug circuit.
04. Commonly Affected Makes
05. 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 engine may be hard to start and run poorly, risking further damage.
How much does it cost to fix?▼
Typically $50-$150 for a single glow plug replacement, including parts and labor. Wiring repairs may add $50-$100.