How to reset the BMW coolant fault lamp causes and remedies

The water temperature indicator is a significant indicator of the health of the car's cooling system and, consequently, of the state of the engine, which, when it overheats, can suffer severe damage. Let's find out together what to do when the light comes on.

What is the water temperature light for?

The water temperature indicator is red, representing a thermometer, and two small waves are located on the dashboard inside the engine coolant temperature indicator. This indicator light is used to signal an abnormal rise in the temperature of the coolant (one of the main causes of engine overheating), which should fluctuate between 80 ° and 90 °.

Like all the other lights on the dashboard, this one also lights up for a few seconds when the car is started, to turn off immediately after. If the light does not go out directly after starting the vehicle, or if it comes on while driving, there is a problem, which could be more or less severe.

When the coolant warning light is on, pull over immediately and turn off the fire as soon as possible without compromising safety. Wait for the engine to cool down before opening the engine's front cover for inspection. The coolant fault light indicates to the driver that the engine or its control system is abnormal and needs to be repaired.

During fuel combustion in a combustion engine, a lot of heat is generated, which must be transferred via special cooling water (also referred to as coolant or coolant) to the radiator and there to the outside air.

The cooling water level is too low if the coolant indicator lamp lights up yellow. The cooling water level should be checked and, if necessary, checked. ATTENTION: The cooling water expansion tank is under pressure. Therefore, only open it when the engine is cold – otherwise, there is a risk of severe scalding.

If the coolant indicator lamp lights up or flashes red, this indicates a too-low cooling water level or a cooling water temperature that is too high. There is a risk of expensive engine damage due to overheating. The engine should be switched off as soon as possible, and the car towed to a workshop.

What does the coolant indicator light look like?

The coolant indicator light indicates a thermometer located in a liquid (two wavy lines). It can light up yellow, red, or flash if it is active.

Water temperature indicator light: possible causes

The water light can come on for various reasons, which can be more or less severe. We list the most frequent.

1. The coolant level is too low (it would be advisable to check it about one time per month).
2. Engine fatigue due to prolonged stops with the vehicle running (the air that cools the radiator is scarce, and the engine overheats), long and sudden climbs, and traffic bottlenecks.
3. Gasket problems.
4. Leaks in the cooling circuit.
5. Damage to the radiator or water pump.
6. Malfunctions of the fan or thermostatic valve.

What to do when the water temperature light comes on?

With the warning light on or flashing, it is always advisable to stop as soon as possible, as continuing the march would only increase the risks for the engine.

If overheating is due to vehicle fatigue, the situation will normalize after the stop, during which it would also be advisable to check the level of coolant in the tank:

• Make sure that no steam comes out of the hood.
• Open the hood.
• Wait at least 20 minutes.
• Carefully unscrew the cap of the liquid tray, using a cloth to avoid burns.
• If the level is low, top up the coolant.

Causes / Significance of an Active Coolant Indicator Light

Among other things, the engine control unit uses sensors to monitor the cooling water level and temperature.

If there are any abnormalities, the coolant indicator light is activated to warn the driver and have the problem rectified.

If the coolant is below the min mark, never continue driving and seek professional assistance immediately. If the coolant is sufficient, it may be an internal engine problem that causes the temperature in the cylinder to be too high and cause an alarm. It should be noted that in either case, the coolant warning light is on, which indicates that the engine temperature is too high. If the engine is not well cooled for a long time, it will cause damage inside the engine.

Therefore, you should check the coolant before travelling in hot weather or driving long distances. The coolant fault light is on this fault to carry out professional fault detection. The test decoder reads the fault code stored in the system and judges the fault's location and cause according to the fault code's prompt. Therefore, it is necessary to go to a professional repair shop in time for testing and not continue to use the vehicle.

What is BMW coolant fluid?

Coolant cools the engine and prevents overheating. There are many different types of commercially available coolant fluids, but it is better to use genuine BMW products to maintain performance.

It is a coolant liquid necessary for car engines, but do you know for what purpose it is used? Coolant fluid has the role of cooling the engine and is used to prevent overheating. You should also take a closer look at the structure of the engine's cooling system to find out what to look out for in the case of a BMW and what can be used instead of coolant.

Coolant cools the engine.

Coolant fluid, also known as long-life coolant, is essential for the engine's proper operation.

While the car engine is running, the interior becomes very hot. If the temperature rises too much, the engine will not be able to demonstrate its performance or may burn, causing problems, so countermeasures have been taken.

When the coolant liquid is circulated using a pump inside the engine, the coolant liquid absorbs the engine's heat, and the temperature can be adjusted.

However, if it is just circulating, the coolant liquid will become too hot, so a cooling device called a radiator is installed.

The radiator has finely jagged parts called fins, which blow the running wind when the hot coolant liquid passes through the channel. The outside temperature is about 40°C even on a hot day, so even if the coolant liquid is hot, it can cool down to about the outside temperature.

It is also fitted with a thermostat regulating cooling water circulation. When the engine is not yet hot, there is no need for cooling, so it is more efficient to circulate without passing through the radiator.

The thermostat is responsible for determining whether the engine needs to be cooled and sending cooling water to the radiator only if it is too hot.

The coolant liquid must also have performance such as "anti-freeze", which does not freeze even when the car is below freezing, and "rust resistance", which does not rust metal parts inside the engine.

BMW turns on the warning light when the coolant decreases

In the engine, gasoline and air mix and cause an explosion, and this phenomenon is used as a power to move the car.

If the coolant decreases, the operating limit temperature of the engine may be exceeded. This is because the temperature inside the engine cannot be properly maintained, and the temperature rises too much. This is called overheating.

To avoid overheating, BMW vehicles display a lamp near the speedometer cluster when the coolant fluid is too low, saying that the coolant level is too low.

When overheating occurs, not only does the engine malfunction, but there is also a risk that the engine will smoke and cause a fire, or the engine will break down and need to be replaced.

Since the radiator is sealed, the coolant does not decrease. If it decreases, there is a risk of liquid leakage, so be careful.

Can we use tap water instead of BMW coolant?

In an emergency, such as when overheating occurs, it is okay to use tap water as a substitute for coolant liquid, but it is important to know that it is only a first aid measure.

Since water has a low specific heat and is easy to heat and cool, it is helpful as an alternative to coolant in terms of cooling.

However, as mentioned earlier, coolant liquids also need to have performed, such as "anti-freezing" and "rust resistance". The main component of the coolant liquid is ethylene glycol, which has a higher boiling point than water and is designed to resist rust.

Tap water contains a variety of substances that can cause rust on metal parts inside the engine. In addition, since water boils at 100°C, if the temperature becomes too high, cavitation may occur and lead to overheating. If tap water is used, do not leave it unattended, and have it inspected at a maintenance shop.

How to refill BMW coolant?

You may not know what to do if you want to replenish the coolant. Here, we will check the procedure for replenishing the coolant liquid and precautions. When opening the radiator cap, it is necessary to check that it is not hot. Let's also check what kind of coolant is suitable for BMW.

Replenishment method

All you need to prepare is a replenishment coolant, a bucket, mug, rag, etc. And with a coolant charger, you can refill the coolant without spilling it.

If the replenishment solution is a dilution type, dilute it to the specified concentration. Open the lid of the reserve tank and pour the refill liquid into the "MAX" part. If you don't have a reserve tank, put it in the radiator. Be careful not to burn yourself when replenishing.

When the coolant has finished refilling, close the reserve tank lid. If the coolant liquid decreases severely, there is a possibility of liquid leakage, so check carefully.

The coolant is colored and therefore dedicated to BMW

Did you know that coolant is colored? Since there are coolant fluids and oils near the car engine, they are colored to make it easier to check which liquid has leaked.

The reason why the colors differ depending on the manufacturer is to differentiate them from other companies. When mixed with coolant from other companies, rust and dirt in the car interior will not only be difficult to find due to discoloration, but it can also lead to water pump malfunction. Therefore, do not use commercial products but replenish BMW-exclusive products.

Do you dilute coolant? Also, diluted products for BMW

There are two types of coolant liquids: replacement stock solution type and replenishment liquid type. The replacement stock solution type is used in dilution due to the high concentration. The replenishment solution is a product made by diluting the replacement stock solution, so it can be used without diluting it with water.

When purchasing, check which type you are before purchasing. By the way, the coolant liquid dedicated to BMW is a type that is used after dilution. When diluting, it is better to avoid using tap water. As mentioned above, tap water contains various components, so there is a risk of problems such as rust. When diluting, use purified water or a special diluent.

Do BMW coolants need leak inhibitors?

Commercially available leak inhibitors include a type that fills a pinhole by increasing the viscosity of the coolant liquid to create a film and a kind that fills the pinhole by liquefying fine fibrous powder and solidifying it by contacting with air.

Leak inhibitors provide a certain effect, but they can also cause malfunctions such as clogging the radiator and overheating the engine. Do not use leak inhibitors blindly; if you feel any abnormality, have it inspected.

Care must be taken when opening the radiator cap.

The radiator cap prevents the coolant liquid from boiling and vaporizing by sealing the radiator. It is also responsible for adjusting the pressure inside the radiator, so care must be taken when opening it.

Pressure is applied inside the radiator when the engine has heat after using the car. Therefore, coolant liquid gushes out when the lid is opened, and burns may occur. When opening the radiator, checking the packing for cracks or deterioration is also safe.

When replenishing coolants such as BMW, bleed air.

When refilling a BMW car with coolant fluid, it is necessary to bleed the air. After refilling the reserve tank and closing the lid, the next step is to remove the radiator cap and start the engine. Then, bubbles form on the liquid surface. These bubbles are air mixed in the cooling channel and escape as bubbles.

If air is mixed in the cooling channel, a sufficient cooling effect may not be obtained, leading to engine damage, so be sure to bleed the air.

Check your car's coolant before it runs out.

If there is a shortage of coolant fluid, there is a risk of problems such as overheating, so regular inspection is required. Let's check how to check the remaining amount of coolant liquid and the approximate replacement time so that you can check it smoothly yourself.

How to check the remaining amount of coolant

First, let's check the water temperature gauge in the car. There is C (cool) and H (heat), and if the needle is pointed in the direction of H, it means that there is an abnormality in cooling. Make sure the needle is pointing in the direction of C.

Next, open the hood and check the remaining cooling water. The reserve tank located in the engine compartment has the signs "MAX" and "MIN"; if the coolant liquid level is between these markings, there is no abnormality. If the liquid level is below "MIN", replenish the coolant liquid.

If the coolant fluid is low, some parts may have a problem, so it is safer to have it inspected by a professional. Places that can be checked include dealerships, car accessory stores, and repair shops. Know the advantages and disadvantages of each store and find the one that suits you.