Collection: Glow Plugs
Glow Plugs — Reliable Diesel Cold Starts, Every Time
Glow plugs are the diesel engine's equivalent of spark plugs — but instead of igniting an air-fuel mixture with an electrical spark, they preheat the combustion chamber to the temperature required for diesel compression ignition. Without properly functioning glow plugs, diesel engines struggle or refuse to start in cold weather, produce excessive white smoke on startup, and may exhibit rough running until the engine reaches operating temperature.
Each cylinder in a diesel engine has its own glow plug, and they typically wear out as a set. Modern glow plugs use an advanced ceramic or metal sheath element that reaches operating temperature within a few seconds of energizing the glow plug system — indicated by the glow plug light on your dashboard. When that light doesn't illuminate, or the engine cranks longer than usual before firing, suspect failing glow plugs.
Signs of Failing Glow Plugs
- Hard starting in cold temperatures (below 40°F / 4°C)
- White smoke from exhaust on startup that clears after warm-up
- Glow plug warning light illuminated on dash
- Check engine light with glow plug circuit fault codes
- Rough idle and misfiring during engine warm-up
Glow plug replacement is often combined with a full diesel tune-up. Pair your glow plug replacement with Motorcraft diesel parts for Ford Powerstroke applications, and don't overlook your ignition maintenance schedule if you also operate gasoline-powered vehicles in your fleet.