Is the coolant indicator light flashing or lit? Consequences and causes!

Recently updated on January 27, 2022 at 10:35 am

If the coolant indicator light flashes or lights up in the car, what is the result and the cause? We have summarized the most important information in this article. When fuel is burned in a combustion engine, it is well known that a lot of heat is generated, which is released via the cooling water (coolant, coolant) directly to the radiator and to the environment. But if the Coolant indicator light lights up yellow, this can, among other things, indicate a too low Be the cooling water level. The manual shows how the cooling water level can be checked and corrected if necessary.

Open the container carefully!

Attention: The expansion tank for the cooling water is under pressure. This should therefore only to be openedwhen the engine has cooled down. Otherwise severe scalding can result. Flashes or shines the indicator light red, this is often an indication that the cooling water level is too low. But also the Cooling water temperature could be too high. Thus, overheating threatens an expensive one engine failure. The engine must therefore be switched off as quickly as possible and the vehicle towed to a workshop. Unfortunately, the causes can be very different. What needs to be considered can be found as follows.

What does the coolant indicator light look like?

The indicator light looks like a Thermometerthat is in a liquid (2 wavy lines). When active, it will glow or flash red or amber. Depending on the vehicle, the messages "Check coolant level", "Engine temperature too high" or similar messages may also (or only) indicate a problem with the engine cooling.

What could be the cause of the active coolant indicator light?

The Engine control unit monitors, among other things, the cooling water temperature and the cooling water level by means of sensors. As soon as there are abnormalities in this area, the indicator light becomes active. The driver is warned so he can fix the problem. The following Causes are possible with an active coolant indicator light:

• Water cooler or cooler leaking
• Cooling water expansion tank defective or leaking
• Cooling water hose defective or leaking
• Cooling circuit sensor defective
• Cable for sensors from the cooling circuit defective
• Coolant pump or water pump defective
• Cylinder head gasket or cylinder head defective

So that the cause can be narrowed down further, the cooling system must be cut off in the workshop. Here the system is pressurized. Thus, the seal or the seals can be checked. If there is a crack or a defective seal anywhere, the pressure test ensures that the leak becomes apparent. If there is a leak in the cooling system, the cause must be determined and remedied.

Are you allowed to continue?

If the indicator light flashes or lights up yellow while the engine is running, the Cooling water level in the expansion tank to be checked. How exactly this works, where the container is located and what needs to be refilled are usually in the vehicle's manual. Is the fill level below the MIN mark, the car should be towed to the workshop. If there is a very large loss of cooling water, the cause should also be determined.

As soon as the cooling water level drops, the temperature of the cooling water continues to rise. If the indicator light comes on suddenly when the engine is running red or flashes, the engine must be switched off immediately and the vehicle must also be towed to the workshop. Otherwise there is a risk of engine damage due to overheating and damage to the cylinder head gasket, for example.

No towing possible - what then?

If the problem occurs while driving, keep an eye on the temperature first. Will be the limit of 100 degrees not exceeded, then one careful onward journey usually still possible at low speed. But if the engine gets hotter, turn off the vehicle and let it cool down. The liquid starts at about 120 degrees Celsius zu . In case of emergancy: Idle pure and heating at full throttle! and im EmergencyMineral water or tap water also works as a coolant.

HU despite the coolant indicator light illuminating?

Cooling water should be topped up immediately if the light flashes or lights up yellow after the engine has started. If the light continues to be active or if the cooling water temperature display shows during the emissions test that the engine is overheating, the main inspection is deemed to be failed.

Cooling water hose / radiator hose broken? The symptoms, repair / replacement and impending costs summarized:

• a component of the cooling water circuit are the cooling water hoses (Radiator hoses / cooling water pipes)
• frequent defects arise due to Marten bites, Oxidation on the pipes and hose clamps, wrong Mounting oder durch porous will
• typical Symptoms / signs for a defective or leaky cooling water hose
  - loss of cooling water (The coolant level in the expansion tank is low)
  - puddle under the car
  - Water vapor from the engine compartment
  - Luminous coolant level indicator light in the instrument cluster
  - the engine is overheating (cooling water temperature display shows a value that is too high / is in the red area)
  - sweet smell from the engine compartment
• Analysis using Check from the expansion tank, inspection of the engine compartment for visually visible damage and traces of cooling water (red, blue or green)
• Continue driving with a defective cooling water hose can damage the engine
• Repair or changing the coolant hose / radiator hose
  - first perform a pressure test (this is used to determine at which point in the cooling water circuit the leak has occurred)
  - Damage directly to the hose (because of marten bite etc.) must be fixed with a new hose
  - It may be that other components have to be dismantled beforehand
  - if the cause of the problem is a loosened / slipped clamp, then dismantle and clean the area and replace it with a new clamp (according to manufacturer specifications)
  - Attention: Drain the cooling water only when the engine is cold!
  - If the hose is changed, then fill the system again with new cooling water and vent it
  - Carry out a final leak test
• Cost of changing a cooling water hose
  - Total costs can vary widely (depends on the hose / pipe and the vehicle)
  - Material costs usually 30 to 350 euros
  - Costs for the new cooling water (around three to five liters at a cost of around 8 to 10 euros per liter)
  - Expenditure for the change depending on the hose / pipe between 20 minutes and 2 hours (Labor costs between 30 and 200 euros)
  - Total costs of around 100 to 600 euros
• Tip: A marten damage is covered by the partial comprehensive insurance (Note the deductible). It is best to use additional hoses jacket protect from hard plastic (slotted corrugated pipes from the hardware store)

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