Heating Core Symptoms on a Honda Civic

Sweet Smell Inside Cab

• The heater core in the Honda Civic transforms engine heat into cab heat. Since the heater core sits under the dash behind the engine firewall, the first symptom of a leak in the heater core is a sweet smell inside the cab. This smell comes from the coolant that runs through the heater core, indicating a small leak has developed there. The seals and tubes to the heater can easily develop a pinhole leak from overheating or deterioration. If this sweet smell develops inside the cab, the Civic owner must take the vehicle to a qualified technician before more expensive damage occurs.

Wet Carpet

• The Honda Civic heater core can cause the carpet inside the cab to become wet — an indication that coolant has leaked out onto the passenger side and onto the carpet and floor mats. In this case, a more severe leak has likely occurred in the heater core and will continue to leak coolant into the cab until repaired. The radiator and engine will continue to lose coolant and will begin to run hot or overheat because of lack of coolant. You should also notice a sweet smell because more coolant has leaked into the Civic. You must have your heater repaired in this case before the engine becomes damaged.

Windows Fogging

• A sure symptom of the heater core in the Honda Civic going bad occurs when the inside windows fog up for no apparent reason. The heater core is not losing liquid coolant in this case; instead, heated coolant will be flowing up through the dash of the Civic and onto the front windshield. In this case, your heater core has likely began leaking or broken a seal, or a hole has developed in one of the hoses. If your windshield begins to fog up while you drive, you must have the heater core repaired immediately to avoid future problems.