Because the sensors detect an active fault, so a DTC is displayed. You'll need to have an OBDII scanner or code reader connected to read that fault in order to know what it is, because there are many different faults which could cause the check engine light to display.
Check your fluid levels.
Fix the problem causing them to be on.
There is an engine misfire, probably spark plugs issue.
To reset the check engine light unplug the battery for 30 minutes. If the issues still persists the light will still light up when reattached.
Get the computer scanned to see what the problem is.
this is for safety so engine does not get ruined,check oil level!!
There are pages and pages of things that can cause a check engine light. You need to have it checked with a scantool. Then the code can be diagnosed and repaired.
Disconnect the negative battery terminal for at least 30 seconds.
If the check engine light is illuminated, start with scanning for codes.
Any failure that can increase tailpipe emissions.
To reset the check engine light on a 2013 Chevy Malibu, you can disconnect the negative battery cable for about 10-15 minutes to clear the engine control unit's memory. Alternatively, you can use an OBD-II scanner to read and clear any stored trouble codes, which will also reset the light. Ensure that any underlying issues causing the check engine light are resolved before resetting it. After reconnecting the battery or using the scanner, the light should turn off.
If your 2001 Chevy Malibu's check engine light is on and the temperature gauge is not functioning, it could indicate a problem with the engine coolant temperature sensor or the gauge itself. Additionally, the check engine light may signal a variety of issues, from minor to serious. It's advisable to use an OBD-II scanner to retrieve any diagnostic trouble codes, which can help pinpoint the problem. Once you have that information, consider consulting a mechanic for a thorough diagnosis and repair.