I have a 2001 monte carlo and the low coolant light came on a few weeks ago. I put in more antifreeze into the car but the message still shows. Now today the check engine light is on but the car is not overheating though. Any ideas on what is wrong and how I can fix it?

 

Most likely it's coincidental for the CEL to come on, but there is a possibility that oil is mixing into the coolant through a leaking lower intake manifold gasket. The oil can leave a film on the coolant level sensor probe, not allowing it to read. I had this problem and replaced the gasket but can't get rid of the tiny bit of oil in the coolant even after have the system professionally flushed and replacing the coolant level sensor twice. I recommend checking the car for diagnostic trouble codes (DTC's) for the CEL.

 

My 2002 Monte Carlo SS 3.8L had low coolant light. Did not get hot, fluid was not low. Flushed radiator, no change. Went to replace low coolant sensor. Price tage $51. Found new sensor on Ebay for $5.95 and free shipping. Change in less than 20 minutes. Problem solved.