You may take best care of your car, keeping the radiator clean and the coolant tank filled. Suddenly your coolant light pops on but the tank is full, what are the possible causes? Some people will drive around with the light on and just ignore it, keeping constant vigilance on the level of the overflow tank, but this is not a good idea.
Your coolant light will usually come on when the sensor senses an incorrect change in the temperature in your system. Typically the sensor, which monitors the coolant temperature, knows how to adjust to different temperatures depending up the status of your vehicle; running, warming up, or cold. The sensor is very important because your vehicle’s systems depend upon it running at defined temperatures. The coolant sensor is also known as the master sensor.
Your sensor may fail or it may just give a bad reading. A bad coolant sensor may cause a decrease in fuel efficiency or it may also make the vehicle to fail your emissions inspection.
It is likely that the issue may be a loose, corroded, or faulty connection and not a problem with the sensor itself. Have all of your connections examined to see if this may be the source of your problem.
Visual diagnoses can sometimes detect an issue with the sensor. You will be able to see if it is cracked or badly corroded. In this case, removal and replacement is necessary. More often than not, though, you will be required to take voltage and resistance readings from the sensor to see if it is functioning properly.
If your vehicle is older, the sensor has deteriorated with time and may be failing but not entirely failed. It is not a bad idea to keep an eye on your sensor’s readings. Changing a sensor that is starting to show extreme signs of age and wear can stop future problems.
You may have some sensor problems that develop from the thermostat rather than the sensor. Your thermostat may be stuck open and causing improper readings. If you recently had your thermostat changed, check to see that it was replaced with the correct size.
Cracked Block or Gasket
Your coolant light might be indications of a more major engine problem. When you get a crack in the block or the intake gasket you will leak coolant and oil, usually slowly at first. You may not observe the difference at first, thinking that your tank is full
A repair to a cracked engine block or head gasket is an expensive repair. While you drive, take note if you smell coolant. That may be an indication of a leak that you haven’t seen yet. Also watch below your vehicle for any telltale drips.
Coolant Level Module
Your problem may also be a faulty coolant level module. Check the wiring to be sure nothing is loose or corroded.
These are some of the possible causes of a coolant light going on when the tank is full. You’ll want to take your vehicle to a qualified repair mechanic to diagnose and repair your problem if you can not easily diagnose it yourself.