Just had my oil changed and now I have a service engine soon light that will not go out

Most likely the air flow sensor was left of the intake hose going from the air filter housing to the air intake of your motor. Also the light may come on if the sensor was released while the key was turned on but the engine was turned off. If you can take a look under your hood and look for the air filter housing. Once you find it follow the Large air hose that goes into the motor. On this hose there should be a sensor plug in for the air flow sensor wire. If there is nothing plugged into try to locate the wire and plug it in. Once you have it plugged in or if it was plugged in try disconnecting your positive battery cable for about 10 minutes to reset the check engine light. Be careful when disconnecting the battery not to touch any metal with the end of your wrench or ratchet. Hope this works for you..