A vehicle coolant system includes a pipe configured to facilitate a flow of vehicle coolant through the pipe, a light source configured to transmit at least one wavelength of light through the vehicle coolant, and a signal detector configured to receive at least one wavelength of light transmitted through the vehicle coolant, and to generate a signal intensity value corresponding to a measured intensity of the at least one wavelength of light received at the signal detector. A controller is configured to receive the signal intensity value from the signal detector, identify a coolant contamination threshold value corresponding to the vehicle coolant, compare the signal intensity value received from the signal detector to the coolant contamination threshold value, and initiate a vehicle coolant remedial action according to a result of comparing the signal intensity value received from the signal detector to the coolant contamination threshold value.