What are 10 OBD modes?

OBD modes provide different functions for diagnosing and solving vehicle issues. Here’s a quick guide to the 10 OBD modes:

Mode $01 – Current Data

Retrieves live data from sensors such as fuel trims, oxygen sensor data, RPM, and temperatures. This data is crucial for diagnosing engine faults. While reading fault codes gives you an idea of what might be wrong, confirming the issue usually requires analyzing live data. For example, a high fuel trim percentage can indicate a vacuum leak, guiding your repair efforts.

Mode $02 – Freeze Frame Data

Captures and stores a snapshot of live data when a fault code is recorded. This freeze frame data includes parameters like RPM, fuel trims, and oxygen sensor readings at the time of the fault. Analyzing this data helps you understand the conditions under which the fault occurred, aiding in accurate diagnosis and repair.

Mode $03 – Diagnostic Trouble Codes

Reads stored Diagnostic Trouble Codes (DTCs) that indicate specific issues detected by the vehicle’s electronic control unit (ECU). While DTCs provide a starting point for diagnosis, further investigation is often needed to identify the exact cause. For instance, a code for an oxygen sensor might require checking fuel delivery and exhaust systems.

Mode $04 – Clear Trouble Codes

Clears stored fault codes and turns off the corresponding dashboard lights, such as the Check Engine Light (CEL). This mode is useful after repairs to reset the system and verify if the issues reoccur. However, permanent faults that still exist will cause the codes and lights to return.

Mode $05 – Test Oxygen Sensors

Tests the functionality of oxygen sensors in older vehicles without CAN bus systems. This mode checks if sensors can accurately detect rich or lean fuel conditions, helping identify issues such as vacuum leaks or faulty injectors that can affect fuel efficiency and emissions.

Mode $06 – Onboard Monitoring

Displays non-continuous test results for various systems, such as oxygen sensors, catalytic converters, and EVAP systems. These results are typically numerical values or thresholds that indicate system performance. Technicians use this data to diagnose intermittent issues that may not trigger immediate fault codes.

Mode $07 – Pending Codes

Shows pending codes from continuous monitors like misfires, fuel system, and comprehensive components. These codes indicate potential issues detected during ongoing system monitoring. If the problem persists, the pending code becomes a confirmed DTC, prompting further diagnostic action.

Mode $08 – Control of Onboard Systems

Allows limited control over certain vehicle components, primarily for testing purposes. Known as bi-directional controls, this mode is often limited to specific tests, such as EVAP system checks. More comprehensive bi-directional control requires advanced diagnostic tools.

Mode $09 – Vehicle Information

Retrieves vital vehicle information, including the Vehicle Identification Number (VIN), calibration IDs, and other manufacturer-specific data. This information is essential for verifying the identity of the vehicle and ensuring the correct parts and procedures are used during repairs.

Mode $0A – Permanent Codes

Reads permanent DTCs that cannot be cleared with a scan tool or by disconnecting the battery. These codes remain stored in the ECU until the issue is resolved and the ECU verifies the repair through its own testing. Permanent codes ensure that significant issues are addressed properly.