What should be done if a vehicle has a persistent check engine light?

When a vehicle has a persistent check engine light, it indicates that the onboard diagnostic system has detected an issue that requires attention. The appropriate action is to use a diagnostic scanner to retrieve the trouble codes stored in the vehicle's computer system. These codes can help identify the specific problem or malfunction that triggered the warning light.

Addressing the underlying issue is essential because ignoring the check engine light or simply checking the oil level does not resolve potential problems. Codes retrieved from the diagnostic scanner guide technicians in troubleshooting and can lead to effective repairs, thus ensuring the vehicle operates safely and efficiently. If left unchecked, underlying issues may lead to increased emissions, decreased performance, and potentially more severe engine damage. Therefore, using a diagnostic scanner is a crucial step in vehicle maintenance when encountering a persistent check engine light.