The glow plug is the replacement of spark plugs, and it is present in vehicles that contain diesel engines. BMW X5 has a diesel engine for the air and diesel mixture burning in the combustion chamber.
BMW X5 glow plugs not working can be due to cold weather, burnt-out glow plugs, a faulty control module, carbon buildup on the cylinder head, faulty electric connections, and insufficient power supply.
These parts last for years, but poor maintenance can affect their longevity. I also spend $300 to $350 for their replacement, with mechanic costs.
|Install block heater
|Faulty glow plug control module
|Replace faulty control modules
|Check voltage supply
|Apply mounting grease
|Carbon buildup on the glow plug and cylinder head
|Use a brass brush for the removal of carbon build-up
|Faulty electric connections
|Inspect frayed connections and replace broken electric wires
|Damaged tip of the glow plug
|Replace burnt-out glow plugs
|Insufficient power supply
|Check batteries power
Cold weather directly affects the functioning of the glow plug. Batteries that provide sufficient current for their heating element also become less effective in low-temperature conditions.
Batteries usually lose their charge during cold weather and become less effective. These plugs require more power from batteries during low temperatures.
One of my friends is a mechanic, and he told me that the replacement ratio of glow plugs during winter is higher than in summer.
He was sharing his experience that he usually replaces 4 to 5 plugs in a day during cold weather because of their decreased effectiveness.
The chances of their failure increase because of the low air temperature and highly viscous diesel fuel. My friend told me that he always recommends the installation of block heaters to keep the engine compartment warm.
Moreover, block heater installation is a reliable option for people who live in cold areas.
Faulty glow plug control module
The glow plug control module controls the functioning of these plugs in BMW vehicles. It controls the functioning of these devices mounted on each cylinder of diesel engines.
It ensures the correct electric current supply required for air and fuel pre-heating. In addition, it also maintains the heating temperature to reduce the overheating and burning chances.
The control module is also vulnerable to failure because of excessive use, high-temperature exposure, injector misfiring, and electric current fluctuations.
The faulty control module does not allow their activation, and it stops functioning. Replacement of the faulty control modules with new ones for better control over the system is necessary.
BMW X5 glow plugs require a specific voltage depending on their type for their functioning. They do not function when the voltage supply is less or more than their requirements.
High voltage current causes the overheating issue, which leads to burnt-out plugs. Some of these devices work on a 12 V current, while others require 6 V.
You should check the voltage supply by using a voltmeter.
Moisture exposure can lead to their failure because of damaged electric connections.
It can also damage the heating element and cannot heat the air and fuel mixture. It causes corrosion on the metal parts, which hinders their normal functioning.
Water can enter inside the engine compartment because of several entry holes. You can face the problem when you drive over the water puddles while off-roading.
Moreover, condensation reactions also leave moisture inside the engine parts. Fuel lines also allow water to enter the engine and damage several components.
Applying mounting grease on plugs is necessary so water exposure cannot corrode their parts.
Mounting grease also acts as a protective layer and reduces the risk of moisture penetration in the thread and shaft.
Carbon buildup on the glow plug and cylinder head
Glow plugs working efficiency decreases because of carbon buildup on their parts. They cannot heat properly to ignite the air and diesel mixture because of soot buildup.
Carbon can accumulate on their surface, cause resistance, and they cannot heat sufficiently. You cannot start the engine properly; it turns off suddenly because of poor heating temperature.
Carbon can build on the plugs because of the incomplete combustion of diesel, which allows the remaining carbon residues to accumulate on the shaft and threads.
Incomplete combustion issues arise in cold weather because of incorrect air and fuel mixtures.
My friend also faced the same issue, and he replaced the glow plugs because of carbon buildup. He told me that he did not turn off the ignition while getting out of his SUV.
Excessive idling leaves carbon residues on the engine parts and decreases their performance. You can also face the issue because of using low-quality diesel fuels.
The problem also comes because of carbon buildup on the cylinder head that does not allow the interaction of the plug and the ignition unit for air and fuel mixture burning.
Always prefer to use high-quality diesel fuels and fuel additives to reduce the risk of carbon accumulation. Moreover, you can also remove the carbon deposits with a brass brush. Move the brush in and out several times to remove soot residues.
Faulty electric connections
Glow plugs are directly connected to your vehicle’s electric system. They take power from your BMW X5 battery for heating purposes. They cannot function and pre-heat the intake air because of poor electric connections.
Bad electric connections do not allow these parts to heat the air and fuel for ignition. The issue comes from broken wires connecting the vehicle’s electric system with these plugs.
Rodents can easily get access to engine components because of the presence of several entry points. In addition, they can also enter the engine because of the open hood and chew electric wires.
Current cannot flow through the broken wires, which can affect the functioning of the respective part. It is necessary for you to keep the hood closed to reduce the chances of rodent entry.
Inspect the electric connections and replace the frayed electric cables with new ones.
Damaged tip of the glow plug
The glow plug is the electric equipment and has a resemblance to the metal pencil. The heating element is located on the tip of this part, which pre-heat the air and fuel to speed up the ignition procedure.
They stop functioning because of damaged or snipped tips. The heating element is the heating coil, which is brittle and can break because of overheating and exposure to high temperatures.
In addition, regular usage also increases the chances of wear and tear on their tip. You can decrease the chances of the damaged tip by maintaining the temperature.
However, you have to replace the plugs with broken tips for their effective functioning. Inspect them and replace the damaged ones with new ones.
Insufficient power supply
Glow plugs require a sufficient power supply for their functioning. They cannot heat the air and diesel fuel mixture because of insufficient power supply.
Insufficient power supply issues arise because of bad electric connections. Broken and loose electric cables affect the current supply.
They take the electric current from the vehicle and use it to heat the heating element. I faced the issue while driving my BMW X5 at night. I started the ignition, but the engine turned off after some time.
I thought it could occur because of cold weather and the increased viscosity of diesel fuel. I called my friend, who told me to check the glow plugs.
I inspected the plugs, but there was no carbon buildup. I checked my SUV batteries because they supply these electric plugs with the current.
I connected the multimeter, which showed a reading of less than 11 V. I recharged the batteries, and it started functioning correctly.