Many malfunctions or issues with important car components are indicated by the illumination of warning lights on the dashboard. This simple way of alerting the driver that something is amiss with the car’s operation is made possible by sensors integrated into these components.
When issues arise with the glow plugs, the glow plug warning light, or preheating warning light, is activated. This warning light typically resembles a spiral and is yellow in color. In this article, we will help you understand:
- What you need to know about glow plugs.
- Why the glow plug warning light illuminates.
- Common glow plug malfunctions.
- Replacing glow plugs in an Volvo XC90 – the procedure and costs.
What You Need to Know About Glow Plugs:
Glow plugs ensure the optimal temperature in the combustion chamber. Their primary purpose is to heat the air in the combustion chamber so that it ignites and subsequently burns the fuel.
Additionally, glow plugs contribute to reducing levels of pollutant emissions resulting from combustion. With the heat generated by glow plugs, the diesel particulate filter (DPF) reaches the right temperature (around 600-700 degrees Celsius) to initiate regeneration and convert PM 2.5 and PM 10 particles into soot.
In the DPF’s operation, glow plugs raise the temperature to start regeneration. More recent glow plugs with instant heating capability can reduce the regeneration interval, which is particularly useful on short drives where regeneration might be interrupted because the drive is completed, and the engine stops.
Due to their roles, glow plugs contribute to achieving good engine performance. When glow plugs no longer function properly or do not function at all, you may experience:
- The engine not reaching the optimal combustion temperature (when running too little).
- The engine reaching excessively high temperatures, which can harm its operation and lead to engine and glow plug damage (when running too long).
Why the Glow Plug Warning Light Illuminates on Volvo XC90:
The glow plug warning light can illuminate in several situations:
In the first situation, which is normal, the warning light comes on when the engine is started. If the indicator on the dashboard goes off after a few seconds, there are no problems.
The second situation, and the most common one, is when one or more glow plugs have burned out.
In the third situation, the brake pedal switch may be the cause, and in this case, you need to confirm whether the brake lights are still working.
The fourth situation involves issues with the pressure and temperature sensor in the intake manifold.
How to Tell If There Are Glow Plug Malfunctions in an Volvo XC90:
Glow plug malfunctions are more challenging to recognize, but there are a few signs that can help:
Illumination of the warning light on the dashboard. If the warning light comes on when you start the car and then goes off, everything is normal. However, if the warning light remains lit on the dashboard, there is a high likelihood of glow plug issues.
White or black smoke emitted from the exhaust pipe.
White smoke appears when fuel does not burn completely due to inadequate temperature in the combustion chamber. In this situation, white smoke and a strong odor are released from the exhaust pipe.
Black smoke indicates an incorrect air-to-fuel ratio, with an excessive amount of fuel being injected.
In practice, when glow plugs have operational issues in an Volvo XC90, you may also encounter:
Harder engine starts, especially in cold weather, when glow plugs fail to provide the necessary temperature in the combustion chamber. This may lead to slower or even failed engine starts.
Engine misfires. Glow plugs can contribute to engine misfires, especially when using lower-quality fuel.
What Can You Do to Extend the Lifespan of Glow Plugs in an Volvo XC90:
Several measures can help maintain glow plugs:
Purchase high-quality glow plugs that adhere to the manufacturer’s recommendations.
Use premium fuel that ensures better engine performance, including the operation of glow plugs.
Adhere to the recommended service intervals for checking the technical condition of glow plugs. Components of the injection system, including glow plugs, the control module, pumps, and injectors, require periodic inspection.
If the glow plug warning light remains lit on the dashboard for more than 20 seconds, it should be checked. It is advisable to visit a service center for this purpose, as they have both specialized personnel and suitable equipment for:
Removing and inspecting the technical condition of glow plugs. This operation includes measuring the ohmic resistance of each glow plug and confirming optimal operating parameters. Not all glow plugs may be defective.
Cleaning the area where glow plugs are installed, reinstalling them, or replacing them if necessary.
Estimated Costs for Replacing Glow Plugs in an Volvo XC90:
The total cost of replacing glow plugs in an Volvo XC90 depends on various factors, such as the car’s year of manufacture, where the glow plugs are purchased (original or aftermarket), and labor costs.
As a rough estimate, the price of glow plugs starts at around 5 euros per piece. If you intend to replace all of them, which is recommended, you will pay at least 25 euros for the parts. It is ideal to buy high-quality glow plugs recommended by the manufacturer, even if they cost more. These components are worth the investment as they do not deteriorate frequently and play a crucial role in the optimal functioning of the engine. Additionally, labor costs will be added to this cost.