What to Do if Check Coolant Warning Light Comes on VW Jetta?

Are you a Volkswagen owner who's recently noticed the coolant warning light on your dashboard? Understanding what this light means and how to respond can be crucial for the health of your vehicle.

A trigger for topping up your engine coolant could be the activation of the engine coolant warning light. Given that the cooling system is a sealed circuit, frequent coolant additions shouldn't be a norm.

What is the cause of this error message?

The problem cause for this error message can be extremely varied. In the simplest case, there is a defect in the expansion tank (coolant loss), the coolant level sensor, the coolant temperature sensor, or the radiator fan. Other causes could also be a porous water hose, a non-functioning radiator fan, or the water pump (housing). All VW, Seat, and Skoda vehicles and models with an onboard computer can be affected by this error message in "text form".

Symptoms: How does the error manifest in the car?

The error is displayed in the onboard computer as a text message "Check coolant! Manual!" or "Coolant system disturbed. Check coolant level!" as well as "Check the coolant level. Observe the manual." Depending on the vehicle model and symptom, a red warning symbol "coolant temperature" and the analog temperature display in the instrument cluster can also draw attention to the problem. After the error message appears, the car should be stopped immediately and the coolant level in the expansion tank should be visually checked. But be careful. Never open the expansion tank while the engine is still hot. A premature opening can lead to severe burns, as the coolant temperature after switching off the engine is still at least 90 degrees and the entire cooling system is also under high pressure.

How can the error be fixed?

After the error message appears, the coolant temperature display in the instrument cluster should be checked first. If the coolant temperature rises and there is always a lack of coolant in the expansion tank, then the error lies elsewhere. The other possible causes must then be determined by a visual inspection. The entire coolant circuit should be examined for visually noticeable water leakage traces. These usually show up in the form of a light crusted deposit. In most cases, the leakage point could also be localized.

Good to know! If a refill of coolant is necessary then (except in an emergency) do not use tap water, but exclusively coolant antifreeze. It is also important to ensure that the coolant has the same color (red, green, blue) as the one previously contained in the cooling system. This is also important to know, as these coolant additives mixed with each other "do not get along". The coolant or the coolant additive (antifreeze) not only serves as frost protection in winter, but it also protects the cooling circuit and the individual cooling components from corrosion.