The engine light is on our 2005 Hemi Jeep Grand Cherokee. What can that mean? We just had the battery, starter and water pump less than one hundred miles ago replaced.

 

There's no point in asking here about why the check engine light is on. The light is on because there is an error code stored in the computer. The computer has detected a problem and stored the code describing the problem and turned on the light. The car must be connected to an appropriate code reader to see what the error code is.

Take the car to someone with a proper code reader (it's a small computer that attaches to a certain plug under the dash) and find out what the code is. Knowing what that code is, a technician can decide what repairs might be necessary. Nobody here can do that.

There are hundreds of error codes for everything from a loose gas cap to a failed engine computer.

Depending on where you live, you may be able to have the codes read for free at an auto parts store. Otherwise, you'll have to pay a service facility to hook up their code reading equipment and diagnose the problem.