Possible causes:
1. Pending Codes: Some vehicles, including older models like the 1995 Chevy Blazer, may store pending trouble codes that have not yet met the criteria to set a permanent code. These pending codes can often be read with a more advanced scan tool than those typically used at auto stores.
2. Intermittent Issues: The service engine soon light can also be triggered by intermittent issues, such as a loose or damaged connection, faulty sensor, or a component that malfunctions sporadically. These types of problems may not be present at the time the vehicle is scanned, leading to the absence of error codes.
3. Emission-Related Issues: In some cases, the service engine soon light may come on due to emissions-related issues, such as a malfunctioning oxygen sensor, catalytic converter problems, or a faulty evaporative emissions control system. These issues may not always trigger specific error codes, particularly in older vehicles.
4. Faulty Sensors: Although you checked for error codes, it's possible that one of the sensors in your vehicle is faulty and not sending a signal to the computer. This could cause the service engine soon light to come on even if there are no error codes.
5. Computer Issues: The computer in your vehicle is responsible for controlling various systems. If the computer is faulty, it may cause the service engine soon light to come on even if there are no error codes.
If the service engine soon light is on and no error codes are present, it's essential to have your vehicle diagnosed by a qualified mechanic who has access to more sophisticated diagnostic equipment. They can further investigate the issue and identify the root cause of the problem.
