Guide

Mode 8 - The bidirectional controls in OBD2

Software OBD2 On-Board Diagnostics

Published on October 17, 2022

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OBD2 was designed mainly for read-only diagnostics. Yet, it has a few bi-directional controls. Test routines defined in Mode 8 are an example of these.

OBD Auto Doctor calls these Mode 8 tests Service Routines. The service routines enable you to control an on-board system, test, or component operation. Basically, the routines allow you to command the vehicle’s on-board system to initiate or perform specific tests.

The Service Routines (Mode 8)

Even though the service currently supports only three routines, it is a rather powerful tool because it can request the vehicle to act.

Evaporative system leak test (TID $01)

This service enables the conditions required to conduct an evaporative system leak test but does not actually run the test. The vehicle manufacturer is responsible for automatically determining the criteria to stop the test.

Particulate Filter Regeneration (TID $02)

This service requests the vehicle to initiate a Particulate Filter (PF) regeneration. The vehicle manufacturer is responsible for determining the criteria to enable, start and stop the test. Previously, this service was called Diesel Particulate Filter (DPF) regeneration.

Inducement System Reinitialization

This service requests the vehicle to initiate the inducement system re-initialization. The vehicle manufacturer is responsible for determining the criteria to enable, start and stop the test. This service is the latest addition to the routines; thus, it may be available only in relatively new cars.

OBD Mode 8 compatibility

As with all features, OBD Auto Doctor requires the vehicle to support Mode 8 to perform the bi-directional controls.

Mode 8 service routines on iPhone (iPhone 14)

Mode 8 service routines on iPhone

You can check if your vehicle has the support with the free version of the software. In mobile, Service Routines are available in the Diagnostics tab. In computer software, you can find the routines in Diagnostics -> Service Routines. Not supported by the ECU means that the selected Electronic Control Unit does not have support for the services. Otherwise, the software lists the supported controls. A paid Premium plan subscription is required to activate a routine.

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