1991 Suzuki Swift Geo Metro 1.0 3 cilinders

That means the Engine Computer has detected a problem, set a diagnostic fault code, and turned the Check Engine light on to tell you. You'll need to find a mechanic with a scanner that can access that computer to read and record the fault code. That will tell you the circuit that needs further diagnosis, or the unacceptable operating condition. Fault codes never say to replace parts or that one is bad, even though a part could be referenced in a fault code.