Glow plug issues on the 6.0L Power Stroke show up as cold-start problems and P067X codes for individual cylinders. The system is similar to the 6.7L but with its own quirks. Here's how we diagnose plugs versus module versus wiring and what the repair runs.
What this issue is
Glow plug issues on the 6.0L Power Stroke produce cold-start problems and related codes. The 6.0L uses eight glow plugs (one per cylinder), each a small electric heating element that warms the combustion chamber during cold-start to assist fuel auto-ignition. A glow plug control module (GPCM) manages power delivery and timing. When plugs or the module fail, cold-start performance drops — sometimes to the point of no-start in cold weather.
The diagnostic and repair approach is similar to the 6.7L Power Stroke glow plug system — see our 6.7L Glow Plug Failure article for the broader pattern. This article covers the 6.0L-specific elements.
Symptoms you’ll notice
- Hard cold-start, especially below 40°F — the most common symptom; starts fine in summer, bad in winter
- Extended cranking before firing in cool or cold weather
- White or gray smoke on cold start, clearing as the engine warms — uncombusted fuel from cylinders not reaching combustion temperature
- Rough idle for the first minute after cold start as affected cylinders lag in contributing
- Check Engine Light with P0670 (module circuit issue) or P0671-P0678 (individual cylinders 1-8)
- Noticeable cylinder miss when cold, smoothing out once the engine reaches operating temperature
- Progressively worse cold-start as outside temperatures drop
- Warm starts work fine — the temperature dependence is the distinctive symptom
The progression is usually — first you notice slightly harder cold starts, then you start getting occasional white smoke, then eventually the first morning you can’t start the truck. By the time it’s a no-start, multiple plugs are often failed and the module may also be compromised.
Why it happens
1. Normal wear of glow plug heating elements. Plugs are heating elements operating in a hot, pressurized combustion chamber. The filament wears over tens of thousands of heat cycles, resistance changes, and eventually the plug can’t generate enough heat to assist cold-start.
2. Electrical issues at specific cylinders. Connector corrosion or damaged wiring at specific cylinders can cause individual circuits to fail even when the plugs are healthy. Diagnostic distinguishes this from plug failure.
3. Glow plug control module failure. The module that powers the plugs and manages timing can fail — producing system-wide cold-start issues and P0670 code. Sometimes module failure presents as multiple individual cylinder codes.
4. Aftermarket plug quality issues. Trucks previously repaired with low-quality aftermarket glow plugs sometimes see early re-failure of those plugs. We’ve also seen low-quality plugs with physical failure — tips breaking off — which can damage pistons. Quality parts matter.
5. Carbon buildup on plug tips. Severe carbon buildup in the combustion chamber can insulate the plug tip and reduce its effectiveness. Less common on well-maintained trucks but seen.
6. Related battery or charging issues. Weak batteries that can’t deliver adequate current to the glow plug system produce cold-start issues that can mimic plug failure. Check batteries before assuming it’s the plugs.
How we diagnose it
Sequence:
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Pull all stored codes. P067X codes identify specific cylinders; P0670 identifies module-side issues. Paired codes give broader picture.
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Resistance test on each glow plug. With the plugs accessed, measure resistance. Healthy plugs read close to each other; plugs reading significantly different are suspect.
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Connector and wiring inspection. Check connectors at each glow plug for corrosion or damage. Follow wiring back to the module for obvious damage.
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Functional test with scan tool. Command the glow plug system on and monitor the module’s report back. Patterns in the data distinguish plug issues from module issues.
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Module voltage and ground check. Verify the module is getting clean power and has good ground reference.
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Battery condition check. Both batteries checked independently. Weak batteries can produce cold-start symptoms that look like plug issues.
What the repair looks like
Individual glow plug replacement. Access the affected plug through the engine bay, disconnect wiring, remove the old plug, install new plug, reconnect and verify function.
Full set of 8 glow plug replacement. Same access labor as individual replacement gives access to all eight. On higher-mileage trucks, this is usually the right scope.
Glow plug control module replacement. When diagnostic identifies module-side issue, replace the module. Moderate access and labor.
Combined module plus full set service. When both module and plugs are compromised (common at high mileage), doing both together leverages the shared access labor.
Wiring or connector repair. Specific to what’s damaged if harness issues are identified.
Pricing
Final pricing depends on labor, parts, and diagnostic findings — we walk through every line item with you before work begins. Call the shop or request an estimate with your year, mileage, and symptoms for a quote on your specific situation.