What does it mean when the glow plug light comes on?
The glow plug light on your vehicle's dashboard is an indicator that the engine's glow plugs are warming up. Glow plugs are essential components in diesel engines that help with cold-weather starting by heating the air in the engine's cylinders before the engine is cranked.
What Are Glow Plugs?
Glow plugs are small, heater-like devices installed in the cylinders of diesel engines. When the engine is cold, the glow plugs heat up the air inside the cylinders to make it easier for the engine to start. This is especially important in cold weather, as diesel engines rely on the heat of compression to ignite the fuel, and cold temperatures can make it difficult for the engine to start.
How the Glow Plug Light Works
The glow plug light on the dashboard is connected to a sensor that monitors the glow plugs. When you turn the key in the ignition, the glow plug light will illuminate, indicating that the glow plugs are heating up. Once the glow plugs have reached the appropriate temperature, the light will turn off, signaling that the engine is ready to be started.
What to Do When the Glow Plug Light Comes On
- Wait for the glow plug light to turn off before starting the engine. This ensures the glow plugs have had enough time to properly heat the air in the cylinders.
- If the glow plug light stays on for an extended period or blinks, there may be an issue with the glow plug system, and you should have your vehicle inspected by a mechanic.
- Driving with the glow plug light on can cause damage to the engine, so it's important to address any issues with the glow plug system as soon as possible.
In summary, the glow plug light is an important indicator that helps ensure your diesel engine starts and runs smoothly, especially in cold weather. By understanding how the glow plug system works and what to do when the light comes on, you can help maintain the health and performance of your vehicle's engine.
Is it safe to drive with a glow plug warning light?
If your glow plug warning light appears, it's important to get help right away. Here are the steps to follow: Do not drive the vehicle. A glow plug warning light may indicate deeper issues with the glow plugs, sensors, or even the engine itself.
What causes a glow plug warning light?
Issues with the diesel glow plug itself, including a loss of heating ability, can cause a blinking glow plug light. There could also be an issue with the timer, which is what regulates how long the glow plugs operate. If the timer is off, it can cause the glow plugs to wear out.
Can I drive my diesel with a bad glow plug?
Yes, you can often drive a diesel with a bad glow plug, but it's not recommended because it can lead to starting difficulties, especially in cold weather, and negatively impact engine performance, fuel economy, and could potentially cause further engine damage. The engine may start, but it might idle roughly, have low power, or produce excessive smoke until it warms up.
How it affects performance
- Starting: It will be harder to start the engine, requiring longer cranking times, and it may not start at all in cold temperatures.
- Rough running: You may experience misfiring, rough idling, and low power.
- Fuel economy: The engine will be less fuel-efficient because it has to work harder to run properly.
- Smoke: Expect more exhaust smoke, particularly white smoke, until the engine reaches its operating temperature.
- Stress on components: Difficulty starting puts extra strain on the battery and starter motor.
Why you should get it fixed
- Prevent further damage: Continuing to drive with a bad glow plug can lead to more expensive engine issues down the road.
- Improve drivability: Replacing the glow plugs will restore your engine's performance and make it more reliable, especially in cold weather.
- Cost savings: While a single glow plug is inexpensive, the potential for more significant engine damage or more frequent starting issues makes prompt replacement worthwhile.
How much does it cost to fix a glow plug?
The cost to replace glow plugs can range from $115 to over $600 for parts and labor, with an average of $450 to $650 for replacing all four. The total price depends on the vehicle's make and model, the number of plugs that need replacing, whether additional components like the glow plug control module need replacing, and labor rates. Parts typically cost $50 to $100 per plug, while labor costs can vary significantly based on accessibility.
You can watch this video to learn how to replace glow plugs in a Duramax engine: 30sDriveway DemonsYouTube · Mar 5, 2022
Cost breakdown and factors
- Parts: Glow plugs typically cost between $50 and $100 each. The total for a set of four might be around $200 to $300.
- Labor: This can be the biggest variable. It depends heavily on how difficult it is to access the plugs. Some jobs might only take an hour, while others can take several hours, especially if parts are seized or difficult to reach.
- Additional parts: The total cost can increase if the glow plug control module or wiring needs to be replaced along with the plugs.
- Diagnostic fees: Some shops charge an initial fee to diagnose the problem, which is then sometimes applied to the final repair bill.
DIY vs. professional repair
- DIY: Replacing glow plugs is often a manageable DIY project if you have the right tools and mechanical knowledge. However, you must be careful, as some glow plugs can be brittle and break during removal, which can lead to a much bigger and more expensive repair involving cylinder head removal.
- Professional: A professional mechanic can handle the job, but the cost will depend on their hourly rate and the time it takes them to complete the repair.
