OBD2 Scanners – What is Mode 1?

Automotive scan tools can be very complex, often challenging the most experience mechanics and technicians. At their very basic, however, they can be easily used by even the mechanical novice for daily tasks like clearing codes and checking emission status. Especially for people who live in states where emissions check are mandatory, having a scan tool can be very handy, helping individuals save money by skipping pricey diagnostic fees.

These tools can interact with many different makes and models, and depending on which tool you buy, you can perform a practically unlimited amount of functions.

But before a scan tool can perform all of those complex functions, it needs to establish a communication process with the vehicle’s computer. This is where Mode 1 comes into play…

Mode 1 Explanation

Before the tool can do anything, it must first know what type of vehicle and what type of engine it is communicating with. Mode 1 is the first step, connecting the scan tool and the vehicle and establishing a common language.

Mode 1 starts the process, showing current data and helping the scan tool establish a usable form of communication with the computer. After Mode 1 is complete, the tool can give freeze frame data, display real-time information, or even give basic error code messages, but it must first use Mode 1 to identify the powertrain.

Mode 1 itself starts by requesting current powertrain diagnostic data, including engine parameters and the check engine light status. While engaging Mode 1 operation, the scan tool will send a signal to the vehicle’s computer, requesting the needed information. Assuming the vehicle’s computer is working properly, the computer will then send the readiness codes and status information.

Clear Communication Thanks to Mode 1

Mode 1 runs quickly, and may even go unnoticed by many users, but it is a vital part of the scan tool process. Whether you’re clearing a basic check engine light, or need to diagnose and repair an engine emissions issue, you wont get very far without good ol’ Mode 1.

Summary of all OBD2 Scanner Modes