OBD2 Scanners – What is Mode 4?

When that pesky check engine light comes on, it can mean many different things for your car’s engine. It could mean you simply need to tighten the gas cap, or it could mean you have a serious engine issue that needs to be immediately addressed by a professional mechanic.

No matter what the severity of the error, you’ll eventually want to clear the code, and make that annoying check engine light disappear. Thanks to Mode 4, you can.

Mode 4: Clear Trouble Codes

Mode 4 is the function that a tool uses to clear all stored trouble codes. After a mechanic connects the tool to the on-board computer, he or she will request the error codes and other information related to the vehicle’s engine. Erasing the codes, however, doesn’t come automatically. Sometimes, you may want to leave the codes and data alone in order to have a professional take a look.

If you do choose to erase the codes, it must be done manually. You or your mechanic will use the scan tool or code reader to send a message to the vehicle’s computer. The tool and car will communicate, usually for a few seconds, and then the check engine light will be erased. The tool will display a message saying the code has been cleared, and often times the vehicle needs to be completely turned off, electrical power and everything. Once the vehicle is restarted, the check engine light should be off.

Mode 4 is available in almost every scan tool and code reader available. Clearing the code is not only important for determining the issue, it’s also important for future codes. If the check engine light stays on and another error occurs, the driver won’t know that a new error code has been generated, leading to a potential issue down the road.

Make the Check Engine Go Away with Mode 4

Whether you choose a large, expensive, advanced scan tool, or choose a simplified code reader, you’ll always use Mode 4 in order to erase that pesky yet important check engine light.

Summary of all OBD2 Scanner Modes