How do I get the service engine soon light to go out

The "Service Engine Soon" comes on when the ECM receives information from the engines sensors that exceeds normal acceptable operating parameters. The ECM will store a code (or codes) indicating which system(s) are out of tolerance and light the "Service Engine Soon" lamp. The technician will read the codes, diagnose and repair the condition(s), and reset the "Service Engine Soon" lamp. The lamp does NOT go out on its own (in most cases), once repairs are made. There is a scan tool that is used to clear the stored codes that allows the lamp to go out. It is therefore possible that you may already have fixed the condition that set your light to on. Or not. The whole purpose of the lamp was to help avoid the kind of "hit and miss" repair methodology that you have employed so far. Many feel the need to try this as they fear the costs of a professional mechanic reading the codes and the cost of repairs. Fortunately, there are less costly options available. Many of the large auto parts chains will read the "Service Engine Soon" codes for you at no cost. They will tell you what codes are present and you can decide if you (or someone you know) can perform repairs or if you need a pro to check things out. They do NOT, normally, perform resets of the lamp as this has potential liability issues for them. If you need the lamp reset after repairs are made, you have two options; pay the pro, or buy a scan tool that has the ability to reset the light. Not all do. The cheaper units are only code READERS. Be careful when you buy. But if you watch for sales, you can usually get a low-cost scan tools that can read and reset codes for around $40.00. Good luck.